\(\left|x+5\right|=3x+1\Leftrightarrow\left[{}\begin{matrix}x+5=3x+1\\x+5=-3x-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}-2x=-4\\4x=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\frac{-3}{2}\end{matrix}\right.\)
b) khong hiểu đề