The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.5698\\[1 em]x_2 &= -0.2151+1.3071i\\[1 em]x_3 &= -0.2151-1.3071i \end{aligned} $$Polynomial $ x^3+x^2+2x+1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.