Question

x-y

x2-y2

+

y-x

y2-x2

=

2

x+y

．

Answer 1

分析：首先将原式变形为

x-y

x2-y2

-

y-x

x2-y2

，然后利用同分母的分式相加减的运算法则求解，注意运算结果要化简．

解答：解：

x-y

x2-y2

+

y-x

y2-x2

=

x-y

x2-y2

-

y-x

x2-y2

=

(x-y)-(y-x)

x2-y2

=

2(x-y)

(x+y)(x-y)

=

2

x+y

．
故答案为：

2

x+y

．

点评：此题考查了分式的加减运算法则．此题比较简单，注意运算结果要化为最简分式．