The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.0668\\[1 em]x_2 &= 11.8014\\[1 em]x_3 &= -12.8682 \end{aligned} $$Polynomial $ x^3-153x+162 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.