Proving Convergence of Sum(a_n)^2: Examples & Explanation

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SUMMARY

The discussion focuses on proving that if the series sum(a_n) converges and each term a_n is non-negative, then the series sum(a_n^2) also converges. A key example provided is the series 1/(n^p) for p > 1, which serves as a valid case for demonstrating convergence. The participant emphasizes the necessity of using rigorous proof rather than relying solely on examples, suggesting the application of the comparison test between a_n and a_n^2 for n ≥ N to establish the convergence of sum(a_n^2).

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  • Understanding of series convergence criteria
  • Familiarity with the comparison test in calculus
  • Knowledge of non-negative sequences
  • Basic concepts of limits and bounds in mathematical analysis
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Homework Statement


Prove that if a_n>or equal to 0, and sum(a_n) converges, then sum(a_n)^2 also converges.


The Attempt at a Solution


The only example I can think of is 1/(n^p) where p is any exponent greater than 1. Are there any other examples that I can use or do I only need to use this example to prove it?
 
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I don't think you can prove something by example.
 
If sum(a_n) converges then there must be an N such that for n>=N, a_n<=1, right? sum(a_n) for n>=N converges. Do a comparison test between a_n and a_n^2 for n>=N.
 
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