The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.4142\\[1 em]x_2 &= 2.4142\\[1 em]x_3 &= -1+1.4142i\\[1 em]x_4 &= -1-1.4142i \end{aligned} $$Polynomial $ x^4-2x^2-8x-3 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.