Can 2^n Always Be Greater Than n for Natural Numbers?

AI Thread Summary
The discussion revolves around proving that for all natural numbers n, 2^n is greater than n using mathematical induction. The base case is established easily, and the inductive hypothesis assumes 2^k > k. The challenge lies in demonstrating that 2^(k+1) > k+1, which can be rewritten as 2^k * 2 > k + 1. Participants emphasize the importance of maintaining the inequality without dropping terms, suggesting that since 2^k > k, it can be used to show that 2^k * 2 also exceeds k + 1. The conversation highlights the nuances of mathematical induction and the need for careful manipulation of inequalities.
amiv4
Messages
24
Reaction score
0

Homework Statement


Prove that for all the natural numbers n that 2^n > n


Homework Equations





The Attempt at a Solution


Base Case is easy
Then the inductive step you have 2^k > k as the inductive hypothesis
show that p[k+1] holds
2^(k+1) > k+1
on the left side 2^(k+1) = 2^k * 2
but idk what else to do
 
Physics news on Phys.org
amiv4 said:

Homework Statement


Prove that for all the natural numbers n that 2^n > n


Homework Equations





The Attempt at a Solution


Base Case is easy
Then the inductive step you have 2^k > k as the inductive hypothesis
show that p[k+1] holds
2^(k+1) > k+1
on the left side 2^(k+1) = 2^k * 2

And what does your induction hypotheses tell you about the 2k on the right side of that last equation? And after you answer that, what are you wanting thge right side of the inequality to be greater than?
 
Well 2^k * 2 > 2^k > k. And I am guessing you are talking about k+1 and idk what i want that to be greater than. It is greater than k but idk how that helps
 
amiv4 said:
Well 2^k * 2 > 2^k > ... And I am guessing you are talking about k+1 and idk what i want that to be greater than. It is greater than k but idk how that helps

But you are giving away something by dropping the 2. You have:

2k+1 = 2k*2 so far, and you know 2k > k

Use that without dropping anything else and see if you can see the result is > k + 1.
 
Back
Top