题目内容
先化简，再求值．| x2-1 |
| x2-2x+1 |
| x2-2x |
| x-2 |
| 3 |
| 2 |
分析：先把分子分母分解因式，再算除法，然后算加法，最后将x=
代入求值即可．
| 3 |
| 2 |
解答：解：原式=
+
×
=
+1
=
+1
=
，
∵x=
，
∴原式=
=
=6．
| (x+1)(x-1) |
| (x-1)2 |
| x(x-2) |
| x-2 |
| 1 |
| x |
=
| (x+1)(x-1) |
| (x-1)2 |
=
| x+1 |
| x-1 |
=
| 2x |
| x-1 |
∵x=
| 3 |
| 2 |
∴原式=
| 2x |
| x-1 |
2×
| ||
|
点评：本题考查了分式的化简求值，解答此题的关键是把分式化到最简，然后代值计算．
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