Question

valorile naturale ale lui 'n' pentru care 18/2n+1  apartin N sunt......
P.S. / =supra

Answer 1

18/2n +1
n = 1 , 3 , 9

18/2x1 = 18/2 = 9+1=10
18/2x3 = 18/6 = 3+1=4
18/2x9 = 18/18 = 1+1=2

Answer 2

$\frac{18}{2n+1}$∈N
2n+1|18
2n+1∈{1,2,3,6,9,18}
2n∈{0,1,2,5,8,17}
n∈{0,$\frac{1}{2}$,1,$\frac{5}{2}$,4,$\frac{17}{2}$} (1)
n∈N (2)
Din (1) si (2) ⇒ n∈{0,1,4}