The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.9181\\[1 em]x_2 &= -0.209+1.261i\\[1 em]x_3 &= -0.209-1.261i \end{aligned} $$Polynomial $ 4x^3-2x^2+5x-6 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.