The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 12.7481\\[1 em]x_2 &= -14.9688\\[1 em]x_3 &= -28.8897+22.9761i\\[1 em]x_4 &= -28.8897-22.9761i \end{aligned} $$Polynomial $ x^4+60x^3+1300x^2-8000x-260000 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.