The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.1036\\[1 em]x_2 &= -0.8086\\[1 em]x_3 &= 1.705 \end{aligned} $$Polynomial $ -7x^3+7x^2+9x-1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.