\(3x+5\)\(⋮\)\(2x+1\)
\(\Leftrightarrow2\left(3x+5\right)\)\(⋮\)\(2x+1\)
\(\Rightarrow6x+10\)\(⋮\)\(2x+1\)
\(\Rightarrow3\left(2x+1\right)+7\)\(⋮\)\(2x+1\)
\(\Leftrightarrow7\)\(⋮\)\(2x+1\)
\(\Rightarrow2x+1\inƯ_7\)Mà \(Ư_7=\left\{\pm1;\pm7\right\}\)
\(\Rightarrow...\)