Question

Aflati n stiind ca 2 n-1 divide pe 9

Answer 1

$D_{9} ={1,3,9}$
1 divide 9 ===>2n-1 divide 9 ===>n=1
3 divide 9 ===>2n-1 divide 9 ===>n=2
9 divide 9 ===>2n-1 divide 9 ===>n=5
n ∈ {1,2,5}