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> 已知a=2+2,求(3aa+1-aa-1)÷aa2-1的值.-数学
已知a=2+2,求(3aa+1-aa-1)÷aa2-1的值.-数学
题目简介
已知a=2+2,求(3aa+1-aa-1)÷aa2-1的值.-数学
题目详情
已知a=2+
2
,求(
3a
a+1
-
a
a-1
)÷
a
a
2
-1
的值.
题型:解答题
难度:中档
来源:保定二模
答案
原式=[
3a(a-1)
(a+1)(a-1)
-
a(a+1)
(a+1)(a-1)
]•
(a+1)(a-1)
a
=
3
a
2
-3a-
a
2
-a
(a+1)(a-1)
•
(a+1)(a-1)
a
=
2
a
2
-4a
(a+1)(a-1)
•
(a+1)(a-1)
a
=
2a(a-2)
(a+1)(a-1)
•
(a+1)(a-1)
a
=2a-4,(4分)
当a=2+
2
时,原式=2(2+
2
)-4=2
2
.(7分)
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题目简介
已知a=2+2,求(3aa+1-aa-1)÷aa2-1的值.-数学
题目详情
答案
=
=
=
=2a-4,(4分)
当a=2+