The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.7522\\[1 em]x_2 &= -0.8761+2.1332i\\[1 em]x_3 &= -0.8761-2.1332i \end{aligned} $$Polynomial $ x^3+x^2+4x-4 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.