题目内容
(2012•工业园区一模)先化简再求值:
+(x-
),其中x=
.
| x-1 |
| x |
| 2x-1 |
| x |
| 3 |
| 2 |
分析:先去括号,再把异分母的分式变成同分母得分式,分母不变,分子相加减,最后代入求出即可.
解答:解:
+(x-
),
=
+x-
,
=
,
=
,
=x-1,
当x=
时,原式=
-1=
.
| x-1 |
| x |
| 2x-1 |
| x |
=
| x-1 |
| x |
| 2x-1 |
| x |
=
| x-1-2x+1+x2 |
| x |
=
| x2-x |
| x |
=x-1,
当x=
| 3 |
| 2 |
| 3 |
| 2 |
| 1 |
| 2 |
点评:本题考查了分式的加减运算,主要考查学生运用法则进行计算的能力,题目比较典型,难度适中.
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