$\text{ ( x - 2 )( 2x - 4 ) = 0}$
$\text{ <=> \(\left[ \begin{array}{l}x-2=0\\2x-4=0\end{array} \right.\) }$
$\text{ <=> \(\left[ \begin{array}{l}x=2\\2x=4\end{array} \right.\) }$
$\text{ <=> \(\left[ \begin{array}{l}x=2\\x=2\end{array} \right.\) }$
$\text{ Vậy S = { 2 } }$