18x²(x-2y)²-24xy(2y-x)²-6x(2y-x)³=18x²(2y-x)²-24xy(2y-x)²-6x(2y-x)³=6(2y-x)²[3x²-4xy-x(2y-x)]=6(2y-x)²[3x²-4xy-2xy+x²]=6（2y-x)²(4x²-6xy)=12x(2y-x)²(2x-3y)x=-3 y=-1=-36*1*(-3)=108
