The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 4.5157\\[1 em]x_2 &= -0.2579+1.1235i\\[1 em]x_3 &= -0.2579-1.1235i \end{aligned} $$Polynomial $ x^3-4x^2-x-6 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.