The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 10.3197\\[1 em]x_2 &= -1.1598+0.77i\\[1 em]x_3 &= -1.1598-0.77i \end{aligned} $$Polynomial $ x^3-8x^2-22x-20 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.