(2x-y)²-4(x-y)(x+2y) 4(-2分之3x-3y)(2分之3x-3y)

问题描述:

(2x-y)²-4(x-y)(x+2y) 4(-2分之3x-3y)(2分之3x-3y)

原式=(4X²-4XY+Y²)-4(X²+XY-2Y²)-4(9/4X²-9XY+9Y²)
=4X²-4XY+Y²-4X²-4XY+8Y²-9X²+36XY-36Y²
=-9X²+28XY-27Y².