The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 3.4236\\[1 em]x_2 &= -2.2118+2.8727i\\[1 em]x_3 &= -2.2118-2.8727i \end{aligned} $$Polynomial $ -x^3-x^2+2x+45 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.