\(\Leftrightarrow\left\{{}\begin{matrix}x^2+x+1=0\\6-2x=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(x+0,5\right)^2+0,75=0\\-2x=-6\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(x+0,5\right)^2=-0,75\left(l\right)\\x=3\end{matrix}\right.\)
Vậy x = 3