The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -2.5874\\[1 em]x_2 &= -0.2063+1.3747i\\[1 em]x_3 &= -0.2063-1.3747i \end{aligned} $$Polynomial $ x^3+3x^2+3x+5 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.