2(x+3y)(x-2y)-3(2x+y)(2x-3y)+5(x-2y)(x+2y)计算,

问题描述:

2(x+3y)(x-2y)-3(2x+y)(2x-3y)+5(x-2y)(x+2y)
计算,

原式=2(x²+xy-6y²)-3(4x²-4xy-3y²)+5(x²-4y²)=2x²+2xy-12y²-12x²+12xy+9y²+5x²-20y²=-5x²+14xy-23y²