The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.6027\\[1 em]x_2 &= -2.2924\\[1 em]x_3 &= 2.8951 \end{aligned} $$Polynomial $ x^3-7x-4 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.