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 |