Question

determinati numarul natural n pentru care 2 n-1 divide pe 18.

Answer 1

2n-1=1,2n=2,n=1,apartina N
2n-1=2,2n=3,n=3/2 nu apartineN
2n-1=3,2n=4,n=2 apartineN
2n-1=6,2n=7,x=7/2 nu apartineN
2n-1=9,2n=10,n=5 apartineN
2n-1=18,2n=19,n=19/2 nu apartine N
n=1,2,5