> 数学 >
先化简,再求值:(
x+2
x2-2x
-
x-1
x2-4x+4
x2-16
x2+4x
,其中x=2+
3

人气:374 ℃ 时间:2020-01-25 12:12:48
解答
原式=[
x+2
x(x-2)
-
x-1
(x-2)2
]
÷
x2-16
x2+4x

=[
x2-4
x(x-2)2
-
x2-x
x(x-2)2
]
÷
x2-16
x2+4x

=
x-4
x(x-2)2
x(x+4)
(x+4)(x-4)

=
1
(x-2)2

x=2+
3
时,
原式=
1
(2+
3
-2)
2

=
1
3
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