The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -1.8664\\[1 em]x_2 &= -0.0668+1.9355i\\[1 em]x_3 &= -0.0668-1.9355i \end{aligned} $$Polynomial $ x^3+2x^2+4x+7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.