7y(x-3y)^2-2(3y-x)^3=7y(x-3y)^2+2(x-3y)^3=(x-3y)^2 [7y+2(x-3y)]=(x-3y)^2 (2x+y)把2x+y=-6,x-3y=4,代入,原式=(x-3y)^2 (2x+y)=16×(-6)= -96
