ĐK: \(0\le x\le7\)
\(2\sqrt{3}-\sqrt{7x-x^2}=0\Leftrightarrow2\sqrt{3}=\sqrt{7x-x^2}\Leftrightarrow12=7x-x^2\)
\(\Leftrightarrow x^2-7x+12=0\Leftrightarrow x^2-4x-3x+12=0\Leftrightarrow x.\left(x-4\right)-3.\left(x-4\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x-4\right)=0\Leftrightarrow x=3\text{ hoặc }x=4\text{. Vậy S=}\left\{3;4\right\}\)