The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -5.3216\\[1 em]x_2 &= 0.6608+3.8205i\\[1 em]x_3 &= 0.6608-3.8205i \end{aligned} $$Polynomial $ x^3+4x^2+8x+80 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.