题目内容
解下列方程:(每小题4分,共16分)
(1)![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013516722.png)
(2)3(x-5)2=2(5-x)
(3)4(x+2)2-9(x-3)2=0
(4)(用配方法解)![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013547605.png)
(1)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013516722.png)
(2)3(x-5)2=2(5-x)
(3)4(x+2)2-9(x-3)2=0
(4)(用配方法解)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013547605.png)
(1)
(2)
(3)
(4)![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013609546.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013563398.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013578705.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013594566.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013609546.png)
试题分析:(1)解:原式可化为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013625562.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013641422.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013563398.png)
(2)解:原式可化为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013672734.png)
若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013687357.png)
方程两边相等
若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013703379.png)
两边同时除以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013719355.png)
即
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013750616.png)
即
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013765500.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013578705.png)
(3)解:原式可化为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013797904.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013812817.png)
解得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013594566.png)
(4)解:原式可化为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013843544.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013859797.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013859808.png)
所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013875723.png)
解得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823023013609546.png)
点评:本题考查的是一元二次方程的求解,通过题目中式子的特殊性,而选去求根公式法、配方法等来解答。
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