The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 5.7607\\[1 em]x_2 &= 15.1197+6.4959i\\[1 em]x_3 &= 15.1197-6.4959i \end{aligned} $$Polynomial $ x^3-36x^2+445x-1560 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.