The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.0806\\[1 em]x_2 &= -1.0806\\[1 em]x_3 &= -5.5527\\[1 em]x_4 &= 5.5527 \end{aligned} $$Polynomial $ x^4-32x^2+36 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.