The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.4467\\[1 em]x_2 &= 2.3623\\[1 em]x_3 &= -0.5045+0.3529i\\[1 em]x_4 &= -0.5045-0.3529i \end{aligned} $$Polynomial $ 5x^4-9x^3-7x^2+2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.