The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.3104\\[1 em]x_2 &= -0.7523\\[1 em]x_3 &= 0.9516 \end{aligned} $$Polynomial $ 9x^3+x^2-7x-2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.