因式分解：25X^2-(X-4Y)^2

25x^2-(x-4y)^2=(5x+x-4y)(5x-x+4y)=8(3x-2y)(x+y)

25X^2-(X-4Y)^2
=(5X)^2-(X-4Y)^2
=[5X+(X-4Y)][5X-(X-4Y)]
=(6X-4Y)(4X+4Y)
=8(3X-2Y)(X+Y)

25X^2-(X-4Y)^2

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

= (6x - 4y)(4x + 4y)

= 8(3x - 2y)(x + y)

25X^2-(X-4Y)^2
=(5x+x-4y)(5x-x+4y)
=8(3x-2y)(x+y)

平方差公式
a^2-b^2=（a+b）*（a-b）
自己带进去看看，记住方法比你只弄懂这一道题要重要的多。。