Ta có : \(3x+14\)\(⋮\)\(3x+1\)
\(\Rightarrow\)\(\left(3x+1\right)+13\)\(⋮\)\(3x+1\)
mà \(3x+1\)\(⋮\)\(3x+1\)
\(\Rightarrow\)\(13\)\(⋮\)\(3x+1\)
\(\Rightarrow\)\(3x+1\in\text{Ư}\left(13\right)\)
\(\Rightarrow\)\(3x+1\in\left\{1;13\right\}\)
\(\Rightarrow\)\(x\in\left\{0;4\right\}\)