X^3 +( x^2)*y - x*(y^2) -y^3 = x^2(x+y) - y^2(x+y)=
= (x + y)(x^2 - y^2) = (x + y)(x + y)(x - y) =
= (x + y)^2 * (x - y)
a^2 + 2ab +b^2 - ac - bc = (a + b)^2 -c(a + b) =
= (a + b)(a + b - c)
xz - yz - x^2 + 2xy - y^2 = z(x - y) -(x^2 - 2xy + y^2) =
= z(x - y) - (x - y)^2 = (x - y)(z - x + y)