题目内容
先化简，再求值：(
+
)÷
，其中x=
-1．
| 1 |
| x+1 |
| x2-2x+1 |
| x2-1 |
| x-1 |
| x+1 |
| 2 |
原式=[
+
]•
=
•
=
，
当x=
-1时，原式=
=-
．
| 1 |
| x+1 |
| (x-1)2 |
| (x+1)(x-1) |
| x+1 |
| x-1 |
=
| x |
| x+1 |
| x+1 |
| x-1 |
=
| x |
| x-1 |
当x=
| 2 |
| ||
|
| ||
| 2 |
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