题目内容
先化简,再求值:
-
-
,其中x=-2.
| x |
| 1+x |
| 1 |
| 1-x |
| x3-2x+1 |
| x2-1 |
| x2-x |
| x2-1 |
| x+1 |
| x2-1 |
| x3-2x+1 |
| x2-1 |
=
| -x3+x2+2x |
| x2-1 |
=
| -x(x2-x-2) |
| (x-1)(x+1) |
=
| -x(x+1)(x-2) |
| (x-1)(x+1) |
=-
| x(x-2) |
| x-1 |
当x=-2时,原式=
| 8 |
| 3 |
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题目内容
| x |
| 1+x |
| 1 |
| 1-x |
| x3-2x+1 |
| x2-1 |
| x2-x |
| x2-1 |
| x+1 |
| x2-1 |
| x3-2x+1 |
| x2-1 |
| -x3+x2+2x |
| x2-1 |
| -x(x2-x-2) |
| (x-1)(x+1) |
| -x(x+1)(x-2) |
| (x-1)(x+1) |
| x(x-2) |
| x-1 |
| 8 |
| 3 |