\(\left|7x\right|=3x+16\) (*)
-ĐK: \(3x+16\ge0\Leftrightarrow3x\ge-16\Leftrightarrow x\ge\dfrac{-16}{3}\)
(*) \(\Leftrightarrow7x=3x+16\) hay \(7x=-3x-16\)
\(\Leftrightarrow4x=16\) hay \(10x=-16\)
\(\Leftrightarrow x=4\left(nhận\right)\) hay \(x=\dfrac{-8}{5}\) (nhận)
-Vậy \(S=\left\{4;\dfrac{-8}{5}\right\}\)