x^3+2x^2-4x-8=0 x^2 (x+2) - 4(x+2) = 0 (x+2) ( x^2 - 4) = 0 x+2 = 0 i x^2 -4 = 0 x=-2 i x^2 = 4 / "V x = +2 i x = - 2