Vì : \(4n+5⋮6n+1\Rightarrow3\left(4n+5\right)⋮6n+1\Rightarrow12n+15⋮6n+1\)
Mà : \(6n+1⋮6n+1\Rightarrow2\left(6n+1\right)⋮6n+1\Rightarrow12n+2⋮6n+1\)
\(\Rightarrow\left(12n+15\right)-\left(12n+2\right)⋮6n+1\)
\(\Rightarrow\left(12n+15-12n-2\right)⋮6n+1\)
\(\Rightarrow13⋮6n+1\)
\(\Rightarrow6n+1\inƯ\left(13\right)\)
Mà : \(Ư\left(13\right)=\left\{1;13\right\}\) ; 6n + 1 là số lẻ
\(\Rightarrow6n+1=1\Rightarrow n=0\)
Vậy n = 0
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