x^3-2x^2y+xy^2-x
=x(x^2-2xy+y^2-1)
=x[(x-y)^2-1]
=x(x-y+1)(x-y-1)
(x^2-x-3)(x^2-x-5)-3
=(x^2-x-3)^2-2(x^2-x-3)-3
=(x^2-x-3+1)(x^2-x-3-3)
=(x^2-x-2)(x^2-x-6)
=(x+1)(x-2)(x+2)(x-3)