The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.8972\\[1 em]x_2 &= -0.9486+1.0163i\\[1 em]x_3 &= -0.9486-1.0163i \end{aligned} $$Polynomial $ 3x^3-5x-11 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.