a) \(\left|5x-4\right|=\left|x+2\right|\)
\(\Rightarrow\left[{}\begin{matrix}5x-4=x+2\\5x-4=-\left(x+2\right)\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}5x-x=2+4\\5x-4=-x-2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}4x=6\\5x+x=\left(-2\right)+4\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=6:4\\6x=2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{3}{2}\\x=\frac{1}{3}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{3}{2};\frac{1}{3}\right\}.\)
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