The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.1314+2.2456i\\[1 em]x_2 &= 0.1314-2.2456i\\[1 em]x_3 &= -5.1314+13.0884i\\[1 em]x_4 &= -5.1314-13.0884i \end{aligned} $$Polynomial $ x^4+10x^3+200x^2+1000 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.