5x^3y(x-y)^3-10x^4y^3(y-x)^2

5x^3y(x-y)^3-10x^4y^3(y-x)^2
=5x^3y(x-y)^3-10x^4y^3(x-y)^2
=5x^3y(x-y)^2[(x-y)-2x]
=5x^3y(x-y)^2(-x-y)
=-5x^3y(x-y)^2(x+y)