tìm n sao cho ... 6n+4 chia hết cho2n+1
...... đúng không bạn?
6n + 4 \(⋮\)2n + 1
=> \(3.\left(2n+1\right)+1⋮2n+1\)
mà \(3.\left(2n+1\right)⋮2n+1\)
nên \(1⋮2n+1\)
\(\Rightarrow2n+1\inƯ\left(1\right)=\left\{1;-1\right\}\)
\(\Rightarrow2n\in\left\{0;-2\right\}\)
\(\Rightarrow n\in\left\{0;-1\right\}\)
Vậy ......