The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 17.0242\\[1 em]x_2 &= -0.0121+0.6411i\\[1 em]x_3 &= -0.0121-0.6411i \end{aligned} $$Polynomial $ x^3-17x^2-7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.