问题 解答题
化简
(1)
a+b
a-b
+
a
b-a

(2)(
2y
y-3
-
y
y+3
)•
y2-9
y
答案

(1)原式=

a+b
a-b
-
a
a-b
=
a+b-a
a-b
=
b
a-b

(2)原式=

2y(y+3)-y(y-3)
(y+3)(y-3)
(y+3)(y-3)
y

=

y2+9y
(y+3)(y-3)
(y+3)(y-3)
y

=

y(y+9)
(y+3)(y-3)
(y+3)(y-3)
y

=y+9.

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