In order to solve $ \color{blue}{ 10x^{4}-18x^{3}-18x = 0 } $, first we need to factor our $ x $.
$$ 10x^{4}-18x^{3}-18x = x \left( 10x^{3}-18x^{2}-18 \right) $$$ x = 0 $ is a root of multiplicity $ 1 $.
The remaining roots can be found by solving equation $ 10x^{3}-18x^{2}-18 = 0$.
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using qubic formulas.