试题与答案

已知x=5-2,求x2-2x+1x2-x-1-2x+x2x-1的值.

题型:解答题

题目:

已知x=
5
-2
,求
x2-2x+1
x2-x
-
1-2x+x2
x-1
的值.

答案:

x=

5
-2,

∴原式=

|x-1|
x(x-1)
-
(x-1)2
x-1

=

1-x
x(x-1)
-(x-1)

=-

1
x
-x+1,

x=

5
-2时,

原式=-

1
5
-2
-
5
+2+1

=-

5
-2-
5
+2+1

=1-2

5

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