问题 解答题
先化简,再求值:
x2-x
x+1
÷(x-1-
2x-2
x+1
)
,其中x=
2
+1
答案

原式=

x(x-1)
x+1
÷
(x2-1-2x+2)
x+1

=

x(x-1)
x+1
x+1
(x-1)2

=

x
x-1

当x=

2
+1时,

原式=

2
+1
2
+1-1
=
2
+1
2
=
2+
2
2

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