(x-y)^2-(2x-y)^2 4x^2-nxy+9y^2

分类: 作业答案 • 2021-12-20 08:54:45

问题描述：

答

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

答

(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