The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 2.1089\\[1 em]x_2 &= -5.9066\\[1 em]x_3 &= -0.6012+1.5902i\\[1 em]x_4 &= -0.6012-1.5902i \end{aligned} $$Polynomial $ x^4+5x^3-5x^2-4x-36 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.