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【330010】15.2.1分式的乘除(1)

时间:2025-02-07 09:17:26 作者: 字数:2277字

 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

15.2.1分式的乘除(1

学习目标

1、理解并掌握分式的乘除法则,运用法则进行简单的分式乘除运算

2、经历探索分式的乘除法运算法则的过程,并能结合具体情境说明其合理性。

3、培养学生的观察、类比、归纳能力和与同伴合作交流的情感

学习重点:掌握分式的乘除运算

学习难点:正确运用分式的基本性质约分

课前预习

阅读课本P135—137

与同伴交流,猜一猜  <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> × <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ÷ <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ac不为

观察上面运算,可知:

分数的乘法法则:________________________________________________________

分数的除法法则:________________________________________________________

你能用类比的方法的出分式的乘除法法则吗?

分式的乘法法则:_________________________________________________________

分式的除法法则:_________________________________________________________

用式子表示为:即 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> × <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ÷ <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>  <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> × <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> = 这里字母abcd都是整式,但acd不为

课内探究

1、计算:{分式乘法运算,进行约分化简,其结果通常要化成最简分式或整式}

1 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> · <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>     (2 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> · <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 3 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>


2 计算:(分式除法运算,先把除法变乘法)

13xy2÷ <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 2 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>3 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ÷ <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>


当堂检测

1、计算:

1 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>2 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>


3 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ÷ <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 4 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> · <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>



5)(a2a÷ <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>




课后训练

1、代数式 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 有意义的 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 的值是( )

A <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> B <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

C <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> D <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

2、甲队在n天内挖水渠a米,乙队在m天内挖水渠b米,如果两队同时挖水渠,要挖x米,需要多少天才能完成?(用代数式表示)




3、若将分式 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 化简得 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> ,则x应满足的条件是( )

A. x0   B. x<0   C.x <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>     D. x <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>

4、若m等于它的倒数,则分式 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 的值为

5、计算(1)  <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> (2). <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>



(3)  <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 4 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>


5 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a> 6 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>


7 <a href="/tags/153/" title="乘除" class="c1" target="_blank">乘除</a> <a href="/tags/846/" title="分式" class="c1" target="_blank">分式</a>