The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 6.2242\\[1 em]x_2 &= 1.8879+0.9666i\\[1 em]x_3 &= 1.8879-0.9666i \end{aligned} $$Polynomial $ x^3-10x^2+28x-28 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.