问题 解答题
化简并求值:(1+
1
x-1
x2
x2-1
,其中x=
2
-1
答案

原式=

x
x-1
÷
x2
x2-1
=
x
x-1
x2-1
x2
=
x
x-1
(x-1)(x+1)
x2
=
x+1
x

x=

2
-1时,原式=
2
2
-1
=2+
2

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