x^2-6xy+9y^2-1=
问题描述：
x^2-6xy+9y^2-1=
答
x^2-6xy+9y^2-1
=(x-y)^2-1
=(x-y+1)(x-y-1)
x^2-6xy+9y^2-1=
x^2-6xy+9y^2-1
=(x-y)^2-1
=(x-y+1)(x-y-1)