The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -2.6458\\[1 em]x_2 &= 2.6458\\[1 em]x_3 &= 1.4142i\\[1 em]x_4 &= -1.4142i \end{aligned} $$Polynomial $ x^4-5x^2-14 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.