因式分解x^2-2xy-8y^2

问题描述:

因式分解x^2-2xy-8y^2

x^2-2xy-8y^2=x^2-2xy+y^2-9y^2=(x-y)^2-(3y)^2=(x-y+3y)(x-y-3y)=(x+2y)(x-4y)