ĐKXĐ; đúng với mọi x vì: \(2x^2-3x+5>0\)
\(2x^2-3x+5=\sqrt{5x^3+4x^2+9x-2}\)
\(\Leftrightarrow\left(2x^2-3x+5\right)^2=5x^3+4x^2+9x-2\)
\(\Leftrightarrow...\Leftrightarrow4x^4-17x^3+25x^2-39x+17=0\)
\(\Leftrightarrow...\Leftrightarrow\left(x-3\right)\left(x-1\right)\left(4x^2-x+9\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=1\\4x^2-x+9=0\left(vn\right)\end{matrix}\right.\)
Vậy \(S\in\left\{1;3\right\}\)