因式分解:x^2-x-9y^2-3y

问题描述:

因式分解:x^2-x-9y^2-3y

x^2-x-9y^2-3y
=( x^2-9y^2)-(x+3y)
=(x+3y)(x-3y)-(x+3y)
=(x+3y)(x-3y-1)

x^2-x-9y^2-3y
=(x^2-9y^2)-(x+3y)
=(x-3y)*(x+3y)-(x+3y)
=(x-3y-1)*(x+3y)

此题利用平方差公式得:
x^2-x-9y^2-3y
=(x+3y)(x-3y)-(x+3y)
=(x+3y)(x-3y-1)

2x-2-6y