题目内容
先化简再求值:(3 |
x-1 |
1 |
x+1 |
x |
x2-1 |
1 |
2 |
分析:先对
-
通分和x2-1分解因式,再约分化简求值.首先要弄清楚运算顺序,先去括号,再进行分式的乘除.
3 |
x-1 |
1 |
x+1 |
解答:解:原式=
÷
=
•
=
当x=
时,原式=10.
3(x+1)-(x-1) |
(x-1)(x+1) |
x |
(x+1)(x-1) |
=
2x+4 |
(x-1)(x+1) |
(x+1)(x-1) |
x |
=
2x+4 |
x |
当x=
1 |
2 |
点评:本题的关键是化简,然后把给定的值代入求值.
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