The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 6.6417\\[1 em]x_2 &= -2.3209+1.563i\\[1 em]x_3 &= -2.3209-1.563i \end{aligned} $$Polynomial $ -x^3+2x^2+23x+52 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.