The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 3.1779\\[1 em]x_2 &= -3.1779\\[1 em]x_3 &= 0.3147i\\[1 em]x_4 &= -0.3147i \end{aligned} $$Polynomial $ x^4-10x^2-1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.