问题 解答题
已知x=3-
2
,求代数式(
x+3
x2-3x
-
x-1
x2-6x+9
x-9
x
的值.
答案

(

x+3
x2-3x
-
x-1
x2-6x+9
x-9
x

=[

x+3
x(x-3)
-
x-1
(x-3)2
]•
x
x-9

=[

(x+3)(x-3)
x(x-3)2
-
(x-1)x
x(x-3)2
]•
x
x-9

=

x2-9-x2+x
x(x-3)2
x
x-9

=

1
(x-3)2

x=3-

2
时,

原式

1
(3-
2
-3)
2
=
1
2

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