x^3+x^2+x-3
=(x^3-x)+(x^2+2x-3)
=x(x^2-1)+(x+3)(x-1)
=x(x+1)(x-1)+(x+3)(x-1)
=(x-1)(x^2+x+x+3)
=(x-1)(x^2+2x+3)