I think you have a typo
Your statement is only true for n = 1
http://www.wolframalpha.com/input/?i=evaluate+3n+%2B+7n+-+2+for+n+%3D+1%2C2%2C3%2C4
Is there supposed to be a power somewhere?
Use mathematical induction to show that
3n + 7n − 2 is divisible by 8 for all n � 1. [Hint: 7n + 1 is divisible by 2.]
1 answer