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

(2)
y3-y
(xy+1)2-(x+y)2
÷
(x+y)y
x+1
,其中x=-11,y=
1
12
答案

(1)原式=

1+x
(x+2)(x-1)
×
x+2
(x+1)(x-1)
=
1
(x-1)2
=
1
(
1
2
-1)
2
=4.

(2)原式=

y(y2-1)
(x2-1)(y2-1)
×
x+1
(x+y)y
=
1
(x-1)(x+y)
=
1
(-11-1)(-11+
1
12
)
=
1
131

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