6x^3y(x-y)^3-4xy^3(y-x)^2
问题描述：
6x^3y(x-y)^3-4xy^3(y-x)^2
答
=6x³y(x-y)³-4xy³(x-y)²
=2xy(x-y)²[3x²(x-y)-2y²]
=2xy(x-y)²(3x³-3x²y-2y²)