Đặt \(x^2-2x+3=t\Rightarrow2x-x^2+6=9-t\)
Pt trở thành:
\(t\left(9-t\right)=18\Leftrightarrow t^2-9t+18=0\)
\(\Rightarrow\left[{}\begin{matrix}t=3\\t=6\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x^2-2x+3=3\\x^2-2x+3=6\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-2x=0\\x^2-2x-3=0\end{matrix}\right.\) (bấm máy)