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`( 2x - 1 ) ( x + 2 ) = ( 3x - 2 ) ( 2x - 1 )`

`<=> ( 2x - 1 ) ( x + 2 ) - ( 3x - 2 ) ( 2x - 1 ) = 0`

`<=> ( 2x - 1 ) ( x + 2 - 3x + 2 ) = 0`

`<=> ( 2x - 1 ) ( 4 - 2x ) = 0`

`<=>` \(\left[ \begin{array}{l}2x-1=0\\4-2x=0\end{array} \right.\) 

`<=>` \(\left[ \begin{array}{l}2x=1\\2x=4\end{array} \right.\) 

`<=>` \(\left[ \begin{array}{l}x=\dfrac{1}{2}\\x=2\end{array} \right.\) 

Vậy `S = { 1/2 ; 2 }`