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

问题描述:

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

16(x-2y)²-25(x+2y)²
=[4(x-2y)+5(x+2y)][4(x-2y)-5(x+2y)]
=(9x+2y)(-x-18y)
=-(9x+2y)(x+18y)