问题 解答题
(1)计算:(-
1
2
)
-1
+(2008-π)0+
3
tan30°

(2)先化简,再求值:
x2-2x
x2-1
÷(x-1-
2x-1
x+1
)
,其中x=
1
2
答案

(1)原式=-2+1+

3
×
3
3

=-2+1+1

=0;

(2)原式=

x(x-2)
(x-1)(x+1)
÷
x2-1-(2x-1)
x+1

=

x(x-2)
(x-1)(x+1)
x+1
x(x-2)

=

1
x-1

当x=

1
2
时,原式=
1
1
2
-1
=-2.

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