x^3-1-3x+3=(x-1)(x^2+x+1)-3(x-1)=(x-1)(x^2+x-4)
x^3 -7x +6
=x^3-x-6(x-1)
=x(x+1)(x-1)-6(x-1)
=(x-1)(x*x+x-6)
=(x-1)(x+3)(x-2)