问题 解答题
计算:
(1)
a+b
5ab
15a2b
a2-b2
;           
(2)
5x+3y
x2-y2
-
2x
x2-y2
答案

(1)原式=

a+b
5ab
15a2b
a2-b2

=

3a
a-b

(2)原式=

5x+3y-2x
x2-y2

=

3(x+y)
(x+y)(x-y)

=

3
x-y

填空题
单项选择题