题目内容
先化简，再求值：(
-
)÷
，并选一个你喜欢的值带入求解．
| x+2 |
| x2-2x |
| x |
| x-2 |
| x-1 |
| x |
原式=（
-
）÷
=
×
=
=
=-
，
当x=-2时，原式=-
=-
．
| x+2 |
| (x-2)x |
| x2 |
| (x-2)x |
| x-1 |
| x |
=
| x+2-x2 |
| (x-2)x |
| x |
| x-1 |
=
| x+2-x2 |
| (x-1)(x-2) |
=
| -(x-2)(x+1) |
| (x-1)(x-2) |
=-
| x+1 |
| x-1 |
当x=-2时，原式=-
| -2+1 |
| -2-1 |
| 1 |
| 3 |
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