分解因式 25（x+y）²-16（x-y）²

25(x+y)^2-16(x-y)^2
=[5(x+y)]^2-[4(x-y)]^2
=[5(x+y)+4(x-y)][5(x+y)-4(x-y)]
=(9x-y)(x+9y)

能简化点么，那些符号不怎么懂！！！！

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

=(5(x+y))^2-(4(x-y))^2

=(5x+5y+4x-4y)(5x+5y-4x+4y)

=(9x+y)(x+9y)

[5（x+y)+4(x-y)][5(x+y)-4(x-y)]=(9x+y)(x+9y)

运用平方差

分解因式 25（x+y)^2-16（x-y）^2;

25（x+y)^2-16（x-y）^2
=[5（x+y)]^2-[4（x-y）]^2
=[5（x+y)+4（x-y）][5（x+y)-4（x-y）]
=(9x+y)(x+9y)