Question

x

x-y

•

y2

x+y

-

x4y

x4-y4

÷

x2

x2+y2

Answer 1

分析：分式的混合运算先乘除运算，把除法运算转化成乘法运算，进行约分，然后进行减法运算，通分化简．

解答：解：原式=

xy2

(x-y)(x+y)

-

x4y

(x2+y2)(x2-y2)

×

x2+y2

x2

=

xy2

(x-y)(x+y)

-

x2y

(x-y)(x+y)

=

xy2-x2y

(x-y)(x+y)

=

xy(y-x)

(x-y)(x+y)

=-

xy

x+y

．
故答案为-

xy

x+y

．

点评：熟练而准确的因式分解是进行分式化简的重要保证，分式的加、减、乘、除混合运算易出现运算顺序方面的错误．