The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.2897\\[1 em]x_2 &= -0.2004+0.6905i\\[1 em]x_3 &= -0.2004-0.6905i \end{aligned} $$Polynomial $ 9x^3-8x^2-6 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.