The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 4.7111\\[1 em]x_2 &= -0.8556+0.5739i\\[1 em]x_3 &= -0.8556-0.5739i \end{aligned} $$Polynomial $ -x^3+3x^2+7x+5 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.