问题 解答题
(1)
a+3b
a+b
+
a-b
a+b

(2)
2xy2+1
(x-y)2
-
1+2x2y
(y-x)2
答案

(1)

a+3b
a+b
+
a-b
a+b

=

a+3b+a-b
a+b

=

2(a+b)
a+b

=2;

(2)

2xy2+1
(x-y)2
-
1+2x2y
(y-x)2

=

2xy2+1-1-2x2y
(x-y)2

=

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

=

2xy
y-x

单项选择题
单项选择题