The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.8171\\[1 em]x_2 &= -0.9086+1.5737i\\[1 em]x_3 &= -0.9086-1.5737i \end{aligned} $$Polynomial $ x^3-6 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.