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【327858】2023年宁夏回族自治区中考数学真题

时间:2025-01-20 20:30:06 作者: 字数:20673字
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2023年宁夏回族自治区中考数学真题

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一、选择题

1. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的绝对值是(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

2.下面是由七巧板拼成的图形(只考虑外形,忽略内部轮廓),其中轴对称图形是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

3.下列计算正确的是(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

4.劳动委员统计了某周全班同学的家庭劳动次数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> (单位:次),按劳动次数分为4组: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,绘制成如图所示的频数分布直方图.从中任选一名同学,则该同学这周家庭劳动次数不足6次的概率是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
A <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

5.估计 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的值应在(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 4之间
B
4 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 之间
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 5之间
D
5 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 之间

6.将一副直角三角板和一把宽度为2cm的直尺按如图方式摆放:先把 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 角的顶点及它们的直角边重合,再将此直角边垂直于直尺的上沿,重合的顶点落在直尺下沿上,这两个三角板的斜边分别交直尺上沿于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 两点,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的长是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
A <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
C
2
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

7.在同一平面直角坐标系中,一次函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的图象如图所示,则下列结论错误的是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
A <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的增大而增大
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
C
.当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
D
.关于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的方程组 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的解为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

8.如图,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 上,且 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,将线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 绕点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 顺时针旋转 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 得到线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的面积是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
A <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

评卷人

得分




二、填空题

9.计算: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ________

10.如图,在边长为2的正方形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 上,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .则图中阴影部分的面积是________
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

11.方程 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 有两个相等的实数根,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的值为________

12.如图,在标有数字1234的四宫格里任选两个小方格,则所选方格中数字之和为4的概率是________
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

13.如图,四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 内接于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,延长 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 至点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,那么 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ________ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

14.如图,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 在数轴上,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示的数是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的中点,线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,则点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示的数是________
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

15.如图是某种杆秤.在秤杆的点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 处固定提纽,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 处挂秤盘,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 0刻度点.当秤盘不放物品时,提起提纽,秤砣所挂位置移动到点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,秤杆处于平衡.秤盘放入 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 克物品后移动秤砣,当秤砣所挂位置与提扭的距离为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 毫米时秤杆处于平衡.测得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的几组对应数据如下表:

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> /

0

2

4

6

10

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> /毫米

10

14

18

22

30

由表中数据的规律可知,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 克时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ________毫米.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    

16.如图是由边长为1的小正方形组成的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 网格,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 均在格点上.下列结论:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 与点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 关于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中心对称;
连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 平分 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,则点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 到线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的距离相等.
其中正确结论的序号是________

评卷人

得分




三、解答题

17.计算: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

18.解不等式组 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
下面是某同学的部分解答过程,请认真阅读并完成任务:
解:由①得:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>              1
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>              2
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>              3
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>              4
任务一:该同学的解答过程第_______步出现了错误,错误原因是_______,不等式①的正确解集是_______
任务二:解不等式②,并写出该不等式组的解集.

19.如图,已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 分别是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 上的点, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .求证:四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 是平行四边形.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    

20.人间烟火味,最抚凡人心”,地摊经济、小店经济是就业岗位的重要来源.某经营者购进了 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型和 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型两种玩具,已知用520元购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量比用175元购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量多30个,且 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具单价是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具单价的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 倍.
(1)
求两种型号玩具的单价各是多少元?
根据题意,甲、乙两名同学分别列出如下方程:
甲: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,经检验 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 是原方程的解.
乙: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,经检验 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 是原方程的解.
则甲所列方程中的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示_______,乙所列方程中的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示_______
(2)
该经营者准备用1350元以原单价再次购进这两种型号的玩具共200个,则最多可购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具多少个?

21.给某气球充满一定质量的气体,在温度不变时,气球内气体的气压 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 是气体体积 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> )的反比例函数,其图象如图所示.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
(1)当气球内的气压超过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时,气球会爆炸.若将气球近似看成一个球体,试估计气球的半径至少为多少时气球不会爆炸(球体的体积公式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 3);
(2)
请你利用 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的关系试解释为什么超载的车辆容易爆胎.

22.如图,粮库用传送带传送粮袋,大转动轮的半径为10cm,传送带与水平面成 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 角.假设传送带与转动轮之间无滑动,当大转动轮转 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时,传送带上点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 处的粮袋上升的高度是多少?(传送带厚度忽略不计)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>       <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    

23.学校组织七、八年级学生参加了“国家安全知识”测试(满分100分).已知七、八年级各有200人,现从两个年级分别随机抽取10名学生的测试成绩 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> (单位:分)进行统计:
七年级   86   94   79   84   71   90   76   83   90   87
八年级   88   76   90   78   87   93   75   87   87   79
整理如下:

年级

平均数

中位数

众数

方差

七年级

84

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

90

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

八年级

84

87

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

根据以上信息,回答下列问题:
(1)
填空: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> _______ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ________
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 同学说:“这次测试我得了86分,位于年级中等偏上水平”,由此可判断他是________年级的学生;
(2)
学校规定测试成绩不低于85分为“优秀”,估计该校这两个年级测试成绩达到“优秀”的学生总人数;
(3)
你认为哪个年级的学生掌握国家安全知识的总体水平较好?请给出一条理由.

24.如图,已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的直径,直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的切线,切点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
(1)求证: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 平分 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,求 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的半径.

25.如图,抛物线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 轴交于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 两点,与 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 轴交于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .已知点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的坐标是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,抛物线的对称轴是直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
(1)直接写出点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的坐标;
(2)
在对称轴上找一点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,使 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的值最小.求点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的坐标和 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的最小值;
(3)
第一象限内的抛物线上有一动点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,过点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 轴,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .依题意补全图形,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的值最大时,求点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的坐标.

26.综合与实践
问题背景
数学小组发现国旗上五角星的五个角都是顶角为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的等腰三角形,对此三角形产生了极大兴趣并展开探究.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
探究发现
如图1,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
1)操作发现:将 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 折叠,使边 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 落在边 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 上,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的对应点是点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,折痕交 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> _______ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,那么 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ______(用含 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的式子表示);
2)进一步探究发现: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,这个比值被称为黄金比.在(1)的条件下试证明: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
拓展应用:
当等腰三角形的底与腰的比等于黄金比时,这个三角形叫黄金三角形.例如,图1中的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 是黄金三角形.如图2,在菱形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .求这个菱形较长对角线的长.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    

参考答案

1.C

【解析】
根据绝对值的性质解答即可.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故选:C

2.C

【解析】
根据轴对称图形的概念进行判断即可.
解:A.不是轴对称图形,故此选项不合题意;
B
.不是轴对称图形,故此选项不合题意;
C
.是轴对称图形,故此选项合题意;
D
.不是轴对称图形,故此选项不符合题意.
故选:C

3.D

【解析】
根据合并同类项,同底数幂的除法,完全平方公式,积的乘方,逐一计算判断即可.
解:A <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,故选项A错误;
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,故选项B错误;
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,故选项C错误;
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,故选项D正确;
故选D

4.A

【解析】
利用概率公式进行计算即可.
解:由题意,得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故选A

5.C

【解析】
先找到所求的无理数在哪两个和它接近的有理数之间,然后判断出所求的无理数的范围.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,排除AD
又∵23更接近25
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 更接近5, 
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 5之间,
故选:C

6.B

【解析】
根据等腰直角三角形的性质可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,由含30度角直角三角形的性质可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,由勾股定理可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的长,即可得到结论.
解:如图,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故选:B

7.C

【解析】
结合图象,逐一进行判断即可.
解:A <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的增大而增大,故选项A正确;
B
、由图象可知,一次函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的图象与 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 轴的交点在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的图象与 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 轴的交点的下方,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,故选项B正确;
C
、由图象可知:当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,故选项C错误;
D
、由图象可知,两条直线的交点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
关于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的方程组 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的解为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故选项D正确;
故选C

8.B

【解析】
证明 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,推出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 为直角三角形,利用 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的面积等于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,进行求解即可.
解:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
将线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 绕点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 顺时针旋转 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 得到线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的面积等于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故选B

9. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
根据同分母分式加法法则计算即可.
解: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

10.2

【解析】
根据正方形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,边长为2,阴影部分面积等于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 面积的和,运用三角形面积公式,即可求解.
四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 为正方形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
正方形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的边长为2
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为:2

11. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
根据方程有两个相等的实数根 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,进行求解即可.
解:∵方程有两个相等的实数根,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

12. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
利用列表法求概率即可.
解:列表如下:


1

2

3

4

1


3

4

5

2

3


5

6

3

4

5


7

4

5

6

7


共有12种等可能的结果,其中和为42种等可能的结果,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

13. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
根据圆周角定理得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,再根据圆内接四边形性质和平角的定义即可得解.
解:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 内接于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

14. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
根据两点间的距离公式和中点平分线段进行计算即可.
解:∵点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的中点,线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示的数是: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

15.50

【解析】
根据表格可得yx的函数关系式,再将 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 代入求解即可.
解:由表格可得,物品每增加2克,秤砣所挂位置与提扭的距离增加4毫米,则物品每增加1克,秤砣所挂位置与提扭的距离增加2毫米,
当不挂重物时,秤砣所挂位置与提扭的距离为10毫米,
yx的函数关系式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为:50

16.①②③

【解析】
根据描述,作图,逐一进行判断即可;
解:①如图:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 与点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 关于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中心对称;故①正确;
如图:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
由图可知: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 为等腰三角形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 经过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的中点,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 平分 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,故②正确;
如图, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 点到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的距离为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 点到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的距离为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 到线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的距离相等,故③正确;
综上,正确的有①②③;
故答案为:①②③.

17. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
先化简各式,在按照运算顺序进行计算即可.
解:原式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

18.任务一:4,不等号的方向没有发生改变, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ;任务二: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
任务一:系数化1时,系数小于0,不等号的方向要发生改变,即可得出结论;
任务二:移项,合并同类项,系数化1,求出不等式②的解集,进而得出不等式组的解集即可.
解:任务一:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
该同学的解答过程第4步出现了错误,错误原因是不等号的方向没有发生改变,不等式①的正确解集是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为:4,不等号的方向没有发生改变, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
任务二: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
不等式组的解集为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

19.见解析

【解析】
根据平行线的性质和判定证得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,再根据平行四边形的判定即可证得结论.
证明: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 是平行四边形.

20.(1) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的单价;购买 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量
(2)
最多购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
1)根据方程表示的意义,进行作答即可;
2)设最多购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 个,根据题意,列出方程进行求解即可.
1)解:对于甲: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示的是:用520元购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量比用175元购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量多30个,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 分别表示 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具和 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的单价;
对于乙: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示的是: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具单价是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具单价的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 倍,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,分别表示表示 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具和 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的单价,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 表示购买 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量;
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的单价;购买 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的数量
2)设购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 个,则购买 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 个,
由(1)中甲同学所列方程的解可知: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的单价为5元,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具的单价为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 元,
由题意,得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 为整数,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
答:最多购进 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 型玩具 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 个.

21.(1)气球的半径至少为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时,气球不会爆炸;
(2)由于车辆超载,轮胎体积变小,胎内气压增大导致爆胎.

【解析】
1)设函数关系式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,用待定系数法可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,即可得当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,从而求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
2)由于车辆超载,轮胎体积变小,胎内气压增大导致爆胎.

1设函数关系式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
根据图象可得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的增大而减小,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 要使气球不会爆炸, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,此时 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 气球的半径至少为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时,气球不会爆炸;
2由于车辆超载,轮胎体积变小,胎内气压增大导致爆胎.

22.粮袋上升的高度是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> cm

【解析】
先求出粮袋移动的距离,再根据含30度角的直角三角形的性质,进行求解即可.
解:如图,设大转动轮转 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时,粮袋移动到点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
则: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
过点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,即:粮袋上升的高度是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> cm

23.(1)8587,七;
(2)220
(3)
八年级,理由见解析

【解析】
1)根据中位数和众数的定义即可求出答案;
2)分别求出七、八年级优秀的比例,再乘以总人数即可;
3)两组数据的平均数相同,通过方差的大小直接比较即可.
1)解:把七年级10名学生的测试成绩排好顺序为:71767983848687909094
根据中位数的定义可知,该组数据的中位数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
八年级10名学生的成绩中87分的最多有3人,所以众数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
A
同学得了86分大于85分,位于年级中等偏上水平,由此可判断他是七年级的学生;
故答案为:8587,七;
2 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> (人),
答:该校这两个年级测试成绩达到“优秀”的学生总人数为220人;
3)我认为八年级的学生掌握国家安全知识的总体水平较好,
理由:因为七、八年级测试成绩的平均数相等,八年级测试成绩的方差小于七年级测试成绩的方差,所以八年级的学生掌握防震减灾科普知识的总体水平较好.

24.(1)见解析
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的半径为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
1)连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,根据切线的性质可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,证明 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,根据平行线的性质和等腰三角形的性质求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 即可;
2)连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,过点O <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> F,证明 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,根据正切的定义列式求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,再根据勾股定理求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 即可.
1)证明:连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的切线,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 平分 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
2)解:连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,过点O <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> F,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的半径为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

25.(1) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的最小值为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
(3)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
1)根据抛物线的对称性,进行求解即可;
2)根据抛物线的对称性,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,得到当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 三点共线时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的值最小,为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的长,求出直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的解析式,解析式与对称轴的交点即为点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的坐标,两点间的距离公式求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的长,即为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的最小值;
3)根据题意,补全图形,设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,将 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的最大值转化为二次函数求最值,即可得解.
1)解:∵点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 关于对称轴的对称点为点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,对称轴为直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
2)当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 关于对称轴的对称点为点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 三点共线时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的值最小,为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的长,
设直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的解析式为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
则: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 在抛物线的对称轴上,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的最小值为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
3)过点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 轴,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,如图所示,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>        
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
设抛物线的解析式为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,则: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
由(2)知:直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 有最大值,此时 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

26.1 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 2)证明见解析,拓展应用: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>

【解析】
1)利用等边对等角求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的长,翻折得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,利用三角形内角和定理求出, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,表示出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 即可;
2)证明 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,利用相似比进行求解即可得出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
拓展应用:连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,延长 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 至点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,使 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 为黄金三角形,进而得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 的长即可.
解:(1)∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 折叠,使边 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 落在边 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 上,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
2)证明:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
整理,得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> (负值已舍掉);
经检验 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 是原分式方程的解.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
拓展应用:
如图,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,延长 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 至点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,使 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>    
在菱形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> 为黄金三角形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a> .即菱形的较长的对角线的长为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1132/" title="宁夏回族自治区" class="c1" target="_blank">宁夏回族自治区</a> <a href="/tags/753/" title="宁夏" class="c1" target="_blank">宁夏</a> <a href="/tags/1167/" title="自治区" class="c1" target="_blank">自治区</a> <a href="/tags/1171/" title="回族" class="c1" target="_blank">回族</a>