问题 解答题
先化简,再求值:(
2
x2-2x
-
1
x2-4x+4
x-4
x
,其中x=
1
2
答案

(

2
x2-2x
-
1
x2-4x+4
x-4
x

=(

2
x( x-2)
-
1
(x-2)2
x-4
x

=(

2(x-2)
x(x-2)2
-
x
x(x-2)2
)•
x
x-4

=

x-4
x(x-2)2
x
x-4

=

1
(x-2)2

当x=

1
2
时,原式=
1
(x-2)2
=
4
9

单项选择题
多项选择题