Câu hỏi của Nguyen An

Question

tìm n thuộc Z sao cho 2n-3chia hết cho n+1

Lightning Farron · Accepted Answer

$2n-3$ chia hết $n+1$

$\Leftrightarrow2n+2-5$ chia hết $n+1$

$\Leftrightarrow2\left(n+1\right)-5$ chia hết $n+1$

Mà $2\left(n+1\right)⋮n+1$ suy ra $5⋮n+1$

$\Rightarrow n+1\inƯ\left(5\right)=\left\{1;-1;5;-5\right\}$

$\Rightarrow n+1\in\left\{0;-2;4;-6\right\}\left(n\in Z\right)$Câu trả lời: $2n-3$ chia hết $n+1$

$\Leftrightarrow2n+2-5$ chia hết $n+1$

$\Leftrightarrow2\left(n+1\right)-5$ chia hết $n+1$

Mà $2\left(n+1\right)⋮n+1$ suy ra $5⋮n+1$

$\Rightarrow n+1\inƯ\left(5\right)=\left\{1;-1;5;-5\right\}$

$\Rightarrow n+1\in\left\{0;-2;4;-6\right\}\left(n\in Z\right)$