Question

Tìm số nguyên n sao cho : 

a) n+18 chia hết cho n+1

b) n+1 chia hết cho 5

Answer 1

a) \(n+18⋮n+1\)

\(\Rightarrow n+18-\left(n+1\right)⋮n+1\)

\(\Rightarrow n+18-n-1⋮n+1\)

\(\Rightarrow17⋮n+1\)

\(\Rightarrow17⋮n+1\)

\(\Rightarrow n+1\in\left\{-1;1;-17;17\right\}\)

\(\Rightarrow n\in\left\{-2;0;-18;16\right\}\left(n\in Z\right)\)

Answer 2

còn ý b nữa bạn

Answer 3

B) \(n+1⋮5\Rightarrow n+1\inƯ\left(5\right)=\left\{\pm1;\pm5\right\}\)

n+1	-5	-1	1	5
n	-6	-2	0	4