来自陈靖波的问题
【(x-y)^2-(2x-y)^24x^2-nxy+9y^2】
(x-y)^2-(2x-y)^24x^2-nxy+9y^2
1回答
2020-09-30 23:31
【(x-y)^2-(2x-y)^24x^2-nxy+9y^2】
(x-y)^2-(2x-y)^24x^2-nxy+9y^2
(x-y)^2-(2x-y)^2
=[(x-y)-(2x-y)][(x-y)+(2x-y)]
=(-x)(3x-2y)
=-x(3x-2y)
4x^2-nxy+9y^2(n=12)
4x^2-12xy+9y^2
=(2x-3y)^2