x(x-y) ²-y(y-x)²=x(x-y) ²-y(x-y)²=(x-y)³18(a-b)³-12b(b-a)²=18(a-b)³-12b(a-b)²=6(a-b)²(3a-5b)x(x+y)(x-y)-x(x+y)²=x(x+y)(-2y)=-2xy(x+y)
