(2x-y)(y+2x)-(2y+x)(2y-x),其中x=1化简求值

(2x-y)(y+2x)-(2y+x)(2y-x)=[(2x²-y²]-[(2y)²-x²]=4x²-y²-4y²+x²=5x²-5y²//(2x-y+3z)(-2x-y-3z)-(x+2y-3z)²=[-y+(2x+3z)][-y-(2x+3z)]-[2y+(x-3z)]²=(-y)²-(2x+3z)²-(2y)²-2(2y)(x-3z)-(x-3z)²=y²-4y²-(4xy-12yz)-(4x²+12xz+9z²)-(x²-6xz+9z²)=-3y²-5x²-18z²-4xy+12yz-6xz=-3*1-5*1-18*1-4(-1)+12(-1)-6*1=-3-5-18+4-12-6=-40直接代入原式=(2+1+3)(-2+1-3)-(1-2-3)²=6*(-4)-(-4)²=-24-16=-40多简单