(1)计算:-22+(12-1)0+2sin30°(2)先化简,再求值x2-1x2-2x+1+x2-2xx-2÷x,其中x=12.-数学

题目简介

(1)计算:-22+(12-1)0+2sin30°(2)先化简,再求值x2-1x2-2x+1+x2-2xx-2÷x,其中x=12.-数学

题目详情

(1)计算:-22+(
1
2
-1
)
0
+2sin30°         
 (2)先化简,再求值
x2-1
x2-2x+1
+
x2-2x
x-2
÷x
,其中x=
1
2
题型:解答题难度:中档来源:不详

答案

(1)原式=-4+1+2×class="stub"1
2

=-4+1+1
=-2;

(2)∵x=class="stub"1
2

∴原式=
(x+1)(x-1)
(x-1)2
+
x(x-2)
x-2
×class="stub"1
x

=class="stub"x+1
x-1
+1,
=class="stub"x+1
x-1
+class="stub"x-1
x-1

=class="stub"2x
x-1

=
2×class="stub"1
2
class="stub"1
2
-1

=-2.

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