$x(x+3)+2x+6=0$ $↔ x(x+3)+2(x+3)=0$ $↔ (x+3)(x+2)=0$ $↔ \left[ \begin{array}{l}x+3=0\\x+2=0\end{array} \right.$ $↔ \left[ \begin{array}{l}x=-3\\x=-2\end{array} \right.$ Bình luận
`x(x+3)+2x+6=0`
`<=>x(x+3)+2(x+3)=0`
`<=> (x+2)(x+3)=0`
`<=> x ∈ { -2 ; – 3 }`
$x(x+3)+2x+6=0$
$↔ x(x+3)+2(x+3)=0$
$↔ (x+3)(x+2)=0$
$↔ \left[ \begin{array}{l}x+3=0\\x+2=0\end{array} \right.$
$↔ \left[ \begin{array}{l}x=-3\\x=-2\end{array} \right.$