\(\sqrt{2013-\sqrt{x-1}}=2014-x\)
⇔ \(\left\{{}\begin{matrix}\sqrt{\dfrac{2014-x}{2013+\sqrt{x-1}}}=2014-x\\x\ge1\end{matrix}\right.\)
⇔ \(\left\{{}\begin{matrix}\sqrt{2014-x}.\left(\dfrac{1}{2013+\sqrt{x-1}}-1\right)=0\\x\in\left[1;2014\right]\end{matrix}\right.\)
⇔ \(\left\{{}\begin{matrix}\left[{}\begin{matrix}\dfrac{1}{2013+\sqrt{x-1}}=1\\x=2014\end{matrix}\right.\\x\in\left[1;2014\right]\end{matrix}\right.\)
⇔ x = 2014
Vậy S = {2014}