The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.3416i\\[1 em]x_2 &= -1.3416i\\[1 em]x_3 &= 1.5119i\\[1 em]x_4 &= -1.5119i \end{aligned} $$Polynomial $ 35x^4+143x^2+144 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.