16（x＋y）² - 25（x-y）²
=[4(X+Y)]²-[5（x-y）]²
=[4(x+y)+5(x-y)][4(x+y)-5(x-y)]
=(4x+4y+5x-5y)(4x+4y-5x+5y)
=(9x-y)(9y-x)
仅仅是个因式分解,求解答因式分解：16（x＋y）² - 25（x-y）² 速度啊
16（x＋y）² - 25（x-y）²
=[4(X+Y)]²-[5（x-y）]²
=[4(x+y)+5(x-y)][4(x+y)-5(x-y)]
=(4x+4y+5x-5y)(4x+4y-5x+5y)
=(9x-y)(9y-x)