The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.3799\\[1 em]x_2 &= -1.7843\\[1 em]x_3 &= 0.7022+0.7003i\\[1 em]x_4 &= 0.7022-0.7003i \end{aligned} $$Polynomial $ 3x^4-5x^2+7x-2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.