问题 解答题
计算:
(1)a-b+
2b2
a+b

(2)
xy
x2-y2
÷(
1
x-y
-
1
x+y
)
答案

(1)原式=

(a-b)(a+b)+2b2
a+b

=

a2+b2
a+b

(2)原式=

xy
(x+y)(x-y)
÷
x+y-x+y
(x+y)(x-y)

=

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

=

x
2

选择题
单项选择题