(1)计算:(-12)-1+(2008-π)0+3tan30°(2)先化简,再求值:x2-2xx2-1÷(x-1-2x-1x+1),其中x=12.-数学

题目简介

(1)计算:(-12)-1+(2008-π)0+3tan30°(2)先化简,再求值:x2-2xx2-1÷(x-1-2x-1x+1),其中x=12.-数学

题目详情

(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
题型:解答题难度:中档来源:不详

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)
class="stub"x+1
x(x-2)

=class="stub"1
x-1

当x=class="stub"1
2
时,原式=class="stub"1
class="stub"1
2
-1
=-2.

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