(1)计算:(1-22)0+(15)-1-2cos45°+|-2|;(2)先化简,再求值:12a-a2-1a2-2a+1÷a2+aa-1,其中a=-12.-数学

题目简介

(1)计算:(1-22)0+(15)-1-2cos45°+|-2|;(2)先化简,再求值:12a-a2-1a2-2a+1÷a2+aa-1,其中a=-12.-数学

题目详情

(1)计算:(
1-
2
2
)
0
+(
1
5
)
-1
-2cos45°+|-
2
|

(2)先化简,再求值:
1
2a
-
a2-1
a2-2a+1
÷
a2+a
a-1
,其中a=-
1
2
题型:解答题难度:中档来源:贵港

答案

(1)原式=1+5-2×
2
2
+
2
=6;

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

=class="stub"1
2a
-class="stub"1
a
=-class="stub"1
2a

当a=-class="stub"1
2
时,
原式=-class="stub"1
2a
=-class="stub"1
2×(-class="stub"1
2
)
=1.

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