How many positive integers 'n' are there such that [(2)^n + 1] is divisible by 7 ?
2^n+1=7k, k positiv integer
in the right member of the equation it should:
for the first: k=even to complete a power of 2
for the second: k=odd cu complete an even number by adding 1.
so 2^n=-1 (impossible)
Posted by luminita
on 2004-01-08 09:56:07