The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 7.07\\[1 em]x_2 &= -0.035+0.7027i\\[1 em]x_3 &= -0.035-0.7027i \end{aligned} $$Polynomial $ 2x^3-14x^2-7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.