[TEX]x^2y^2(y-x)+y^2z^2(z-y)-z^2x^2(z-x) \\ = x^2y^3-x^3y^2+y^2z^3-y^3z^2-z^2x^2(z-x) \\ = (y^2z^3-y^2x^3)-(y^3z^2-x^2y^3)-z^2x^2(z-x) \\ = y^2(z^3-x^2)-y^3(z^2-x^2)-z^2x^2(z-x) \\ = y^2(z-x)(z^2+zx+x^2)-y^3(z-x)(z+x)-z^2x^2(z-x) \\ = (z-x)(y^2z^2+y^2zx+y^2x^2-y^3z-y^3x-z^2x^2) \\ = (z-x)[(y^2z^2-z^2y^2)-(y^3z-y^2zx)-(y^3x-y^2x^2)] \\ = (z-x)[z^2(y-x)(x+y)-y^2z(y-x)-y^2x(y-x)] \\ = (z-x)(y-x)(z^2x+z^2y-y^2z-y^2x) \\ = (z-x)(y-x)[zy(z-y)+x(z-y)(z+y)] \\ = (z-x)(y-x)(z-y)(yz+xz+xy)[/TEX]