81(x-y)^2-16(x+y)^2

问题描述:

81(x-y)^2-16(x+y)^2
分解因式

[9(x-y)]^2-[4(x+y)]^2 平方差公式
[9(x-y)+4(x+y)][9(x-y)-4(x+y)]^2
[13x-5y)(5x-13y)