Gọi ƯCLN(2n + 1,n + 1) = d
Ta có : \(\hept{\begin{cases}2n+1⋮d\\n+1⋮d\end{cases}}\)=> \(\hept{\begin{cases}2n+1⋮d\\2\left(n+1\right)⋮d\end{cases}}\)=> \(\hept{\begin{cases}2n+1⋮d\\2n+2⋮d\end{cases}}\)
=> (2n + 2) - (2n + 1) \(⋮\)d
=> \(2n+2-2n-1⋮d\)
=> 1 \(⋮\)d
=> d = 1