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

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Discussion Overview

The discussion centers around proving that for all natural numbers n, the inequality 2^n > n holds. The scope includes mathematical reasoning and inductive proof techniques.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • Some participants present a base case for the inequality as straightforward and propose an inductive step where they assume 2^k > k to prove 2^(k+1) > k+1.
  • One participant questions what the inductive hypothesis implies about the right side of the inequality, specifically regarding the term 2k.
  • Another participant expresses uncertainty about what the right side of the inequality should be greater than, acknowledging that it is greater than k but unsure how that aids the proof.
  • There is a suggestion to retain the factor of 2 in the expression 2^(k+1) = 2^k * 2 and to utilize the established inequality 2k > k to derive the desired result.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the next steps in the proof, and there is ongoing uncertainty about how to effectively apply the inductive hypothesis.

Contextual Notes

Participants have not fully resolved the implications of their inductive hypothesis, and there are missing assumptions regarding the behavior of the terms involved in the inequality.

amiv4
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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
 
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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.
 

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