x^6(x-1)-x^5(x-1)^2=x^5(x(x-1)-(x-1)^2)=x^5(x-(x-1))(x-1)
x^4(x-3)-x^3(x-3)^2=x^3(x(x-3)-(x-3)^2)=x^3(x-(x-3))(x-3)
x^6(x-1)-x^5(x-1)^2=x^5(x(x-1)-(x-1)^2)=x^5(x-(x-1))(x-1)
x^4(x-3)-x^3(x-3)^2=x^3(x(x-3)-(x-3)^2)=x^3(x-(x-3))(x-3)