The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.3005\\[1 em]x_2 &= -1.34\\[1 em]x_3 &= 0.5198+1.4877i\\[1 em]x_4 &= 0.5198-1.4877i \end{aligned} $$Polynomial $ x^4+x^2+3x-1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.