The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.8872\\[1 em]x_2 &= -1.8872\\[1 em]x_3 &= 0.7494i\\[1 em]x_4 &= -0.7494i \end{aligned} $$Polynomial $ x^4-3x^2-2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.