The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.5818\\[1 em]x_2 &= -2.0409+1.6461i\\[1 em]x_3 &= -2.0409-1.6461i \end{aligned} $$Polynomial $ 2x^3+7x^2+9x-8 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.