In order to solve $ \color{blue}{ -x^{5}+5x^{3}-2x = 0 } $, first we need to factor our $ x $.
$$ -x^{5}+5x^{3}-2x = x \left( -x^{4}+5x^{2}-2 \right) $$$ x = 0 $ is a root of multiplicity $ 1 $.
The remaining roots can be found by solving equation $ -x^{4}+5x^{2}-2 = 0$.
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using quartic formulas