Đáp án: $n\in\{-2,-1,1,2,7,17,-4,-5,-7,-8,-13,-23\}$
Giải thích các bước giải:
Để $7n+41$ là bội của $n+3$
$\to 7n+41\quad\vdots\quad n+3$
$\to 7n+21+20\quad\vdots\quad n+3$
$\to 7(n+3)+20\quad\vdots\quad n+3$
$\to 20\quad\vdots\quad n+3$
$\to n+3\in U(20)$
$\to n+3\in\{1,2,4,5,10,20,-1,-2,-4,-5,-10,-20\}$
$\to n\in\{-2,-1,1,2,7,17,-4,-5,-7,-8,-13,-23\}$