题目是不是错了,应该是(2x+y)^2-(x+2y)^2 (2x+y)^2-(x+2y)^2 =[(2x+y)+(x+2y)]*[(2x+y)-(x+2y)] =(3x+3y)(x-y) =3(x+y)(x-y)
4x^2+4xy+y^2-x+2y
