The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 5.7638\\[1 em]x_2 &= -6.4758\\[1 em]x_3 &= -10.288 \end{aligned} $$Polynomial $ x^3+11x^2-30x-384 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.