Proof of Inequality by Induction

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SUMMARY

The discussion focuses on proving the inequality \( n^3 \leq 3^n \) for all natural numbers \( n \) using mathematical induction. Participants emphasize the importance of establishing a base case and an inductive step, particularly for \( n \geq 3 \). A hint is provided suggesting that if \( n \geq 3 \), then \( (n+1)^3 \leq \left(n + \frac{n}{3}\right)^3 \) can be utilized to facilitate the proof. This structured approach confirms the validity of the inequality through rigorous mathematical reasoning.

PREREQUISITES
  • Understanding of mathematical induction
  • Familiarity with polynomial and exponential functions
  • Basic algebraic manipulation skills
  • Knowledge of inequalities and their properties
NEXT STEPS
  • Study the principles of mathematical induction in detail
  • Explore proofs involving inequalities, specifically polynomial versus exponential growth
  • Learn about the binomial theorem and its applications in proofs
  • Investigate other examples of induction proofs in number theory
USEFUL FOR

Students in mathematics, educators teaching proof techniques, and anyone interested in deepening their understanding of mathematical induction and inequalities.

sbrajagopal2690
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need help on this

Show by induction that n^3 <= 3^n for all natural numbers n.
 
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Re: Proof of Inequlity by Induction

sbrajagopal2690 said:
need help on this

Show by induction that n^3 <= 3^n for all natural numbers n.
Hint: If $n\geqslant 3$ then $(n+1)^3 \leqslant \bigl(n+\frac n3\bigr)^3$.
 

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