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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