计算:(1/3x+y)(1/3x-y)(1/9x2+y2).

问题描述:

计算:(

1
3
x+y)(
1
3
x-y)(
1
9
x2+y2).

原式=[(

1
3
x)2-y2](
1
9
x2+y2
=(
1
9
x2-y2)(
1
9
x2+y2
=(
1
9
x22-(y22
=
1
81
x4-y4