Question

Tìm các số tự nhiên n sao cho
a.  2n - 32⋮n+3

b. 5n-49⋮n+5

 

 

Answer 1

a) \(\Rightarrow2\left(n+3\right)-38⋮\left(n+3\right)\)

Do \(n\in N\)

\(\Rightarrow\left(n+3\right)\inƯ\left(38\right)=\left\{19;38\right\}\)

\(\Rightarrow n\in\left\{16;35\right\}\)

b) \(\Rightarrow5\left(n+5\right)-74⋮\left(n+5\right)\)

Do \(n\in N\)

\(\Rightarrow\left(n+5\right)\inƯ\left(74\right)=\left\{37;74\right\}\)

\(\Rightarrow N\in\left\{32;69\right\}\)