ta có : \(x\left(4+x\right)=-3\Leftrightarrow x^2+4x+3=0\Leftrightarrow x^2+x+3x+3=0\) \(\Leftrightarrow x\left(x+1\right)+3\left(x+1\right)=\left(x+3\right)\left(x+1\right)=0\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x+1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=-1\end{matrix}\right.\) vậy \(x=-3\) hoặc \(x=-1\)
