The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.8434\\[1 em]x_2 &= -0.1717+0.7768i\\[1 em]x_3 &= -0.1717-0.7768i \end{aligned} $$Polynomial $ 6x^3-9x^2-7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.