Question

Tìm n ∈ N để:

a, n+4 ⋮ n

b, 3n+7 ⋮ n

c, 27 - 5n ⋮ n, (n < 6)

Answer 1

a, Ta có: n+4 ⋮ n => 4 ⋮ n => n ∈ {1;2;4}

b, Ta có: 3n+7 ⋮ n => 7 ⋮ n => n ∈ {1;7}

c, Ta có: 27 - 5n ⋮ n => 27 ⋮ n => n ∈ {1;3;9;27}

Do n < 6. Vậy n ∈ {1;3}