问题 解答题
化简下列各题.
(1)
m2-2m
4-m2

(2)
x-y
x2-2xy+y2

(3)
b
a-b
+
a
a+b
-
2ab
b2-a2

(4)(
1
b
-
1
a
)•
ab
a2-b2
答案

(1)原式=

m(m-2)
-(m+2)(m-2)

=-

m
m+2

(2)原式=

x-y
(x-y)2

=

1
x-y

(3)原式=

b(a+b)+a(a-b)+2ab
(a+b)(a-b)

=

(a+b)2
(a+b)(a-b)

=

a+b
a-b

(4)原式=

a-b
ab
ab
(a+b)(a-b)

=

1
a+b

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