Question

tìm các số tự nhiên n sao cho 

3n+4 chia hết cho n+1

n+4 chia hết cho n+1

Answer 1

a) \(3n+4⋮n+1\)

\(3\left(n+1\right)+1⋮n+1\)

\(\Rightarrow1⋮n+1\)

\(\Rightarrow n+1\inƯ\left(1\right)\)

\(\Rightarrow n+1\in\left\{1;-1\right\}\)

\(\Rightarrow n\in\left\{0;-2\right\}\)

Vậy ..................

b) \(n+4⋮n+1\)

\(n+1+3⋮n+1\)

\(\Rightarrow3⋮n+1\)

\(\Rightarrow n+1\inƯ\left(3\right)\)

\(\Rightarrow n+1\in\left\{1;3;-1;-3\right\}\)

\(\Rightarrow n\in\left\{0;2;-2;-4\right\}\)

Vậy ................