$(x -3)(2x +1) = (3x -5)(x -3)$
$⇔ (x -3)(2x +1) - (3x -5)(x -3) = 0$
$⇔ (x -3).(2x +1 -3x +5) = 0$
$⇔ (x -3).(-x +6) = 0$
$⇔ \left[ \begin{array}{l}x -3=0\\-x +6=0\end{array} \right. ⇔ \left[ \begin{array}{l}x=3\\x=6\end{array} \right.$
$Vậy$ $S =$ {$3; 6$}
