Question

n+ 3 chia hết cho n +1           tìm số tự nhiên n để

6n + 12 chia hết cho 3n+4

6n+3  chia hết cho 3n+6

Answer 1

1) \(\left(n+3\right)⋮\left(n+1\right)\)

\(\Rightarrow\left(n+1\right)+2⋮\left(n+1\right)\)

\(\Rightarrow\left(n+1\right)\inƯ\left(2\right)=\left\{-2;-1;1;2\right\}\)

Do \(n\in N\)

\(\Rightarrow n\in\left\{0;1\right\}\)

2) \(\Rightarrow2\left(3n+4\right)+4⋮\left(3n+4\right)\)

\(\Rightarrow\left(3n+4\right)\inƯ\left(4\right)=\left\{-4;-2;-1;1;2;4\right\}\)

Do \(n\in N\)

\(\Rightarrow n\in\left\{0\right\}\)

3) \(\Rightarrow2\left(3n+6\right)-9⋮\left(3n+6\right)\)

\(\Rightarrow\left(3n+6\right)\inƯ\left(9\right)=\left\{-9;-3;-1;1;3;9\right\}\)

Do \(n\in N\)

\(\Rightarrow n\in\left\{1\right\}\)