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【330014】15.2.2分式的加减(1)

时间:2025-02-07 09:17:45 作者: 字数:2623字

 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

15.2.2 分式的加减(1

学习目标

1、经历探索分式加减运算法则的过程,理解其算理

2、会进行简单分式的加减运算,具有一定的代数化归能力

3、不断与分数情形类比以加深对新知识的理解

学习重点同分母分数的加减法

学习难点通分后对分式的化简

课前预习

一、温故知新:阅读课本P139—141

1、计算并回答下列问题

 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

2、同分母分数如何加减?

3、猜一猜,同分母的分式应该如何加减?(同分母分数加减进行类比)

4、把你猜想的结论用数学符号表示出来

1、计算:

点拨:

如果结果不是最简分式,怎么办?

1 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> + <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 2 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>





2计算:1). <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> - <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> (2) <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>



课内探究

1、填空题

(1)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> = (2)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> =

2、在下面的计算中,正确的是( )

A. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> + <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> = <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> B. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> = <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

C. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> = <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> D. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> =0

3计算:

1 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>2 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

4、老师出了一道题“化简: <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

小明的做法是:原式 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

小亮的做法是:原式 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

小芳的做法是:原式 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

其中正确的是( )

A、小明 B、小亮 C、小芳 D、没有正确的

当堂检测

1、化简 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 的结果是( )

(A)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> (B)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> (C)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> (D)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

2、甲、乙2港分别位于长江的上、下游,相距s km,一艘游轮往返其间,如果游轮在静水中的速度是a km/h,水流速度是b km/h,那么该游轮往返2港的时间差是多少?


3计算: (1)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 2 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>






课后训练

1、已知x <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> , <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 等于( )

A. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> B. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> C. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> D. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

2、化简 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 可得到( )

A.B.零次多项式 C.一次多项式 D.不为零的分式

3、分式 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 的最简公分母是( )

A.5abx B.15ab <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> C.15abx D.15ab <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

  1. 在分式 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ;③ <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 中分母相同的分式是( )

A.①③④ B.②③ C.②④ D.①③

5、下列算式中正确的是( )

A. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ; B. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ; C. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ; D. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

6.x 克盐溶解在a克水中,取这种盐水m克,其中含盐( )

A. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> B. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> C. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> D. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

7. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ;

8. <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ;

9.ab=2,a+b=-1, <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 的值为 ;

10.计算 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ;

11计算

(1)  <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 2 <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>