`y10000`
`2x . ( x + 3 ) - 4x - 12 = 0`
`<=> 2x . ( x + 3 ) - 4 . ( x + 3 ) = 0`
`<=> ( 2x - 4 ) . ( x + 3 ) = 0`
`<=>` \(\left[ \begin{array}{l}2x-4=0\\x+3=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=2\\x=-3\end{array} \right.\)
$\text{Vậy}$ \(\left[ \begin{array}{l}x=2\\x=-3\end{array} \right.\)