Question

3. Tìm số tự nhiên n biết

a) 24 + n⋮ n

b) 15 – n ⋮𝑛

c) n + 15⋮𝑛+3

d) 2n + 9⋮𝑛+2

Answer 1

\(24+n⋮n\Rightarrow24⋮n\)

\(\Rightarrow n\in\left\{1;2;3;4;6;8;12;24\right\}\)

Answer 2

b) \(15-n⋮n\Rightarrow15⋮n\)

\(\Rightarrow n\in\left\{1;3;5;15\right\}\)

Answer 3

\(n+15⋮n+3\)

\(\Rightarrow12⋮n+3\)

\(\Rightarrow n+3\in\left\{3;4;6;12\right\}\)

\(\Rightarrow n\in\left\{0;1;3;9\right\}\)

Answer 4

\(2n+9⋮n+2\)

\(\Rightarrow5⋮n+2\)

\(\Rightarrow n+2=5\)

\(\Rightarrow n=3\)

Answer 5

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