Question 320897
If you can see that x = -1 is one root, it is easy now :-)
x^3 - 5x^2 +2x + 8 = x^3 + x^2 - 6x^2 - 6x + 8x - 8 = x^2(x+1) - 6x(x+1) + 8(x+1) = (x+1)(x^2 - 6x +8) 
Easy, right?