The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.0452+0.5709i\\[1 em]x_2 &= -0.0452-0.5709i\\[1 em]x_3 &= 5.0452+3.3362i\\[1 em]x_4 &= 5.0452-3.3362i \end{aligned} $$Polynomial $ x^4-10x^3+36x^2+12 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.