(1)计算:(92)-1-(-3.14)0+12-1-sin30°•cos45°.(2)已知a2+2a-3=0,求(a-2a2+2a-a-1a2+4a+4)÷a-4a+2的值.-数学

题目简介

(1)计算:(92)-1-(-3.14)0+12-1-sin30°•cos45°.(2)已知a2+2a-3=0,求(a-2a2+2a-a-1a2+4a+4)÷a-4a+2的值.-数学

题目详情

(1)计算:(
9
2
)-1-(-3.14)0+
1
2
-1
-sin30°•cos45°

(2)已知a2+2a-
3
=0,求(
a-2
a2+2a
-
a-1
a2+4a+4
a-4
a+2
的值.
题型:解答题难度:中档来源:不详

答案

(1)原式=
2
3
-1+
2
+1-class="stub"1
2
×
2
2

=
13
2
12

(2)原式=[class="stub"a-2
a(a+2)
-class="stub"a-1
(a+2)2
]•class="stub"a+2
a-4

=class="stub"a-4
a(a+2) 2
class="stub"a+2
a-4

=class="stub"1
a2+2a

∵a2+2a-
3
=0,
∴a2+2a=
3

∴原式=class="stub"1
3
=
3
3

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