题目内容
已知x=-
，对代数式
+
先化简，再求值．
| 3 |
| 2 |
| x2 |
| x-1 |
| 1 |
| 1-x |
原式=
-
=
=
=x+1，
当x=-
时，原式=-
．
| x2 |
| x-1 |
| 1 |
| x-1 |
=
| x2-1 |
| x-1 |
=
| (x-1)(x+1) |
| x-1 |
=x+1，
当x=-
| 3 |
| 2 |
| 1 |
| 2 |
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题目内容
| 3 |
| 2 |
| x2 |
| x-1 |
| 1 |
| 1-x |
| x2 |
| x-1 |
| 1 |
| x-1 |
| x2-1 |
| x-1 |
| (x-1)(x+1) |
| x-1 |
| 3 |
| 2 |
| 1 |
| 2 |