Question

Tìm n ∈ N, biết: a) n + 4 ⋮ n b) 3n + 7 ⋮ n c) 27 - 5n ⋮ n d) n + 6 ⋮ n + 2

Answer 1

a) \(n+4⋮n\)

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

Do n\(\in N\)

\(\Rightarrow n\in\left\{1;2;4\right\}\)

b) \(\Rightarrow n\inƯ\left(7\right)=\left\{-7;-1;1;7\right\}\)

Do \(n\in N\)

\(\Rightarrow n\in\left\{1;7\right\}\)

c) \(\Rightarrow n\inƯ\left(27\right)=\left\{-27;-9;-3;-1;1;3;9;27\right\}\)

Do \(n\in N\)

\(\Rightarrow n\in\left\{1;3;9;27\right\}\)

d) \(\Rightarrow\left(n+2\right)+4⋮\left(n+2\right)\)

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

Do \(n\in N\)

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