2x=4x+18
=>2x-4x=18
=>-2x=18
=>x=18:(-2)
=> x= -9
Chúc cậu may mắn
\(|2x|=4x+18\\\leftrightarrow 2x=4x+18\quad or\quad 2x=-4x-18\\\leftrightarrow -2x=18\quad or\quad 6x=-18\\\leftrightarrow x=-9\quad or\quad x=-3\)
Ta có: \(\left|2x\right|=4x+18\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=4x+18\\-2x=4x+18\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x-4x=18\\-2x-4x=18\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}-2x=18\\-6x=18\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-9\\x=-3\end{matrix}\right.\)
Vậy: \(x\in\left\{-9;-3\right\}\)
