The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.5898\\[1 em]x_2 &= -0.4616+1.1201i\\[1 em]x_3 &= -0.4616-1.1201i \end{aligned} $$Polynomial $ 3x^3-2x^2-7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.