试题

题目:
(2009·上海)计算:
2a+2
a-f
÷(a+f)-
a2-f
a2-2a+f

答案
解:
2a+2
a-1
÷(a+1)-
a2-1
a2-2a+1

=
2(a+1)
a-1
·
1
a+1
-
(a+1)(a-1)
(a-1)2

=
2
a-1
-
a+1
a-1

=
2-a-1
a-1
=-1

解:
2a+2
a-1
÷(a+1)-
a2-1
a2-2a+1

=
2(a+1)
a-1
·
1
a+1
-
(a+1)(a-1)
(a-1)2

=
2
a-1
-
a+1
a-1

=
2-a-1
a-1
=-1
考点梳理
分式的混合运算.
分式分母能约分的先约分,然后把除法运算转化成乘法运算,再进行加减运算.
点拨:本题按照分式化简的步骤,本着化除为乘、先分解后约分、化异为同的思想来解答.
计算题.
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