The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -3.9287+6.7791i\\[1 em]x_2 &= -3.9287-6.7791i\\[1 em]x_3 &= -26.0713+30.809i\\[1 em]x_4 &= -26.0713-30.809i \end{aligned} $$Polynomial $ -x^4-60x^3-2100x^2-16000x-100000 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.