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【334337】2023年天津高考数学真题

时间:2025-01-21 18:03:14 作者: 字数:16019字
简介:

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Shape2

绝密·启用前

2023年天津高考数学真题

题号

总分

得分






注意事项:

1.答题前填写好自己的姓名、班级、考号等信息

2.请将答案正确填写在答题卡上



评卷人

得分




一、单选题

1.已知集合 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>        
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

2. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是“ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ”的(       
A
.充分不必要条件
B
.必要不充分条件
C
.充分必要条件
D
.既不充分又不必要条件

3. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的大小关系为(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

4.函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的图象如下图所示,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的解析式可能为(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>        
A <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

5.已知函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的一条对称轴为直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,一个周期为4,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的解析式可能为(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

6.已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 为等比数列, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 为数列 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的前 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项和, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的值为(       
A
3
B
18
C
54
D
152

7.调查某种群花萼长度和花瓣长度,所得数据如图所示,其中相关系数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,下列说法正确的是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
A.花瓣长度和花萼长度没有相关性
B
.花瓣长度和花萼长度呈现负相关
C
.花瓣长度和花萼长度呈现正相关
D
.若从样本中抽取一部分,则这部分的相关系数一定是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

8.在三棱锥 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中,线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 上的点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 满足 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 上的点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 满足 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则三棱锥 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 和三棱锥 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的体积之比为(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

9.双曲线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的左、右焦点分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 作其中一条渐近线的垂线,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的斜率为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则双曲线的方程为(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

评卷人

得分




二、填空题

10.已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是虚数单位,化简 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的结果为_________

11. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的展开式中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项的系数为_________

12.过原点的一条直线与圆 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 相切,交曲线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,若 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的值为_________

13.若函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 有且仅有两个零点,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的取值范围为_________

评卷人

得分




三、双空题

14.甲乙丙三个盒子中装有一定数量的黑球和白球,其总数之比为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .这三个盒子中黑球占总数的比例分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .现从三个盒子中各取一个球,取到的三个球都是黑球的概率为_________;将三个盒子混合后任取一个球,是白球的概率为_________

15. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的中点,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的中点,若设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 可用 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 表示为_________;若 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的最大值为_________

评卷人

得分




四、解答题

16. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中,角 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 所对的边分別是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(1)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的值;
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的值;
(3)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

17.三棱台 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中,若 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 分别是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中点.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
(1)求证: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> //平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(2)
求平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 与平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 所成夹角的余弦值;
(3)
求点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 到平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的距离.

18.设椭圆 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的左右顶点分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,右焦点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(1)
求椭圆方程及其离心率;
(2)
已知点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是椭圆上一动点(不与端点重合),直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 轴于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,若三角形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的面积是三角形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 面积的二倍,求直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的方程.

19.已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是等差数列, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(1)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的通项公式和 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(2)
已知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 为等比数列,对于任意 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,若 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(Ⅰ)当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,求证: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(Ⅱ)求 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的通项公式及其前 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项和.

20.已知函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(1)
求曲线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 处切线的斜率;
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,证明: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(3)
证明: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

参考答案

1.A

【解析】
对集合B求补集,应用集合的并运算求结果;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,而 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
故选:A

2.B

【解析】
根据充分、必要性定义判断条件的推出关系,即可得答案.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 不成立,充分性不成立;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,显然 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 成立,必要性成立;
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的必要不充分条件.
故选:B

3.D

【解析】
根据对应幂、指数函数的单调性判断大小关系即可.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> R上递增,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 上递增,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
故选:D

4.D

【解析】
由图知函数为偶函数,应用排除,先判断B中函数的奇偶性,再判断AC中函数在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 上的函数符号排除选项,即得答案.
由图知:函数图象关于y轴对称,其为偶函数,且 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 且定义域为R,即B中函数为奇函数,排除;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即AC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 上函数值为正,排除;
故选:D

5.B

【解析】
由题意分别考查函数的最小正周期和函数在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 处的函数值,排除不合题意的选项即可确定满足题意的函数解析式.
由函数的解析式考查函数的最小周期性:
A
选项中 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> B选项中 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
C
选项中 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> D选项中 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
排除选项CD
对于A选项,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,函数值 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是函数的一个对称中心,排除选项A
对于B选项,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,函数值 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是函数的一条对称轴,
故选:B.

6.C

【解析】
由题意对所给的递推关系式进行赋值,得到关于首项、公比的方程组,求解方程组确定首项和公比的值,然后结合等比数列通项公式即可求得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的值.
由题意可得:当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>        
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>              
联立①②可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
故选:C.

7.C

【解析】
根据散点图的特点可分析出相关性的问题,从而判断ABC选项,根据相关系数的定义可以判断D选项.
根据散点的集中程度可知,花瓣长度和花萼长度有相关性,A选项错误
散点的分布是从左下到右上,从而花瓣长度和花萼长度呈现正相关性,B选项错误,C选项正确;
由于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是全部数据的相关系数,取出来一部分数据,相关性可能变强,可能变弱,即取出的数据的相关系数不一定是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> D选项错误
故选:C

8.B

【解析】
分别过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> . <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> , <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .先证 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则可得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,再证 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .由三角形相似得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,再由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 即可求出体积比.
如图,分别过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> . <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> , <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
又因为平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,且 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中,因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中,因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
故选:B

9.D

【解析】
先由点到直线的距离公式求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .再由三角形的面积公式得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,从而得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则可得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,代入双曲线的方程即可得到答案.
如图,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,不妨设渐近线方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> , <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以双曲线的方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
故选:D

10. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ## <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
由题意利用复数的运算法则,分子分母同时乘以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,然后计算其运算结果即可.
由题意可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .

11. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
由二项式展开式的通项公式写出其通项公式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,令 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 确定 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的值,然后计算 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项的系数即可.
展开式的通项公式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 可得, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项的系数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
故答案为:60.

12. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
根据圆 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 和曲线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 关于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 轴对称,不妨设切线方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即可根据直线与圆的位置关系,直线与抛物线的位置关系解出.
易知圆 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 和曲线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 关于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 轴对称,不妨设切线方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,同理可得.
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

13. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
根据绝对值的意义,去掉绝对值,求出零点,再根据根存在的条件即可判断 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的取值范围.
1)当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,此时 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 成立;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
若方程有一根为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
若方程有一根为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,此时 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 成立.
2)当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,显然 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 不成立;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
若方程有一根为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
若方程有一根为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,显然 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 不成立;
综上,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,零点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,零点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,只有一个零点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,零点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,只有一个零点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,零点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时,零点为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以,当函数有两个零点时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

14.      <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>       <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ## <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
先根据题意求出各盒中白球,黑球的数量,再根据概率的乘法公式可求出第一空;
根据古典概型的概率公式可求出第二个空.
设甲、乙、丙三个盒子中的球的个数分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以总数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以甲盒中黑球个数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,白球个数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
甲盒中黑球个数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,白球个数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
甲盒中黑球个数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,白球个数为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
记“从三个盒子中各取一个球,取到的球都是黑球”为事件 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
记“将三个盒子混合后取出一个球,是白球”为事件 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
黑球总共有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 个,白球共有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 个,
所以, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

15.      <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>       <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
1:根据向量的线性运算,结合 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的中点进行求解;空2:用 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 表示出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,结合上一空答案,于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 可由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 表示,然后根据数量积的运算和基本不等式求解.
1:因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的中点,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
两式相加,可得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
2:因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中,根据余弦定理: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 和基本不等式, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,当且仅当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 取得等号,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 有最大值 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    

16.(1) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(3)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
1)根据正弦定理即可解出;
2)根据余弦定理即可解出;
3)由正弦定理求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,再由平方关系求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即可由两角差的正弦公式求出.
1)由正弦定理可得, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
2)由余弦定理可得, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> (舍去).
3)由正弦定理可得, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,而 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 都为锐角,因此 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

17.(1)证明见解析
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(3)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>

【解析】
1)先证明四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是平行四边形,然后用线面平行的判定解决;
2)利用二面角的定义,作出二面角的平面角后进行求解;
3)方法一是利用线面垂直的关系,找到垂线段的长,方法二无需找垂线段长,直接利用等体积法求解
1 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> . <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 分别是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的中点,根据中位线性质, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> // <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,且 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
由棱台性质, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> // <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> // <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 可知,四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 是平行四边形,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> // <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> //平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
2)过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,又 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,又 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .于是平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 与平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 所成角即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
3[方法一:几何法]
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,作 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,过 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,垂足为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
由题干数据可得, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,根据勾股定理, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,又 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,于是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,又 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 到平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的距离是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 到平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的距离的两倍,
即点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 到平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的距离是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
[
方法二:等体积法]
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
辅助线同方法一.
设点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 到平面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的距离为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .

18.(1)椭圆的方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,离心率为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .

【解析】
1)由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,从而求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,代入椭圆方程即可求方程,再代入离心率公式即求离心率.
2)先设直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的方程,与椭圆方程联立,消去 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,再由韦达定理可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,从而得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 点和 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 点坐标. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即可得到关于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的方程,解出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,代入直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的方程即可得到答案.
1)如图,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>    
由题意得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以椭圆的方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,离心率为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
2)由题意得,直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 斜率存在,由椭圆的方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
设直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
联立方程组 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,消去 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 整理得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
由韦达定理得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> , <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> , <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的方程为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .

19.(1) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(2)(Ⅰ)
证明见解析;(Ⅱ) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,前 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项和为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .

【解析】
(1)
由题意得到关于首项、公差的方程,解方程可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,据此可求得数列的通项公式,然后确定所给的求和公式里面的首项和项数,结合等差数列前 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项和公式计算可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
(2)(Ⅰ)
利用题中的结论分别考查不等式两侧的情况,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,取 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即可证得题中的不等式;
(Ⅱ)
结合(Ⅰ)中的结论,利用极限思想确定数列的公比,进而可得数列的通项公式,最后由等比数列前 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项和公式即可计算其前 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项和.
1)由题意可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
则数列 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的通项公式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
求和得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
2(Ⅰ)由题意可知,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,此时 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
据此可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
综上可得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
(Ⅱ)
(Ⅰ)可知: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
则数列 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 的公比 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 满足 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以数列的通项公式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
其前 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 项和为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .

20.(1) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
(2)
证明见解析
(3)
证明见解析

【解析】
1)利用导数的几何意义求斜率;
2)问题化为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,构造 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,利用导数研究单调性,即可证结论;
3)构造 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,作差法研究函数单调性可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,再构造 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,应用导数研究其单调性得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 恒成立,对 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 作放缩处理,结合累加得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即可证结论.
1 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 处的切线斜率为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
2)要证 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即证 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 上递增,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .
3)设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
由(2)知: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 上递减,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
下证 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 递增,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 递减,
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> 恒成立,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,…, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
累加得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,而 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
因为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
所以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,故 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a>
综上, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/1180/" title="天津" class="c1" target="_blank">天津</a> .


Shape4 3页,总1