Absolute Convergence Proof: The Relationship Between a_k and b_k

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SUMMARY

The discussion centers on the proof of absolute convergence, specifically addressing the statement: if \( a_k \le b_k \) for all \( k \in \mathbb{N} \) and \( \sum_{k=1}^{\infty} b_k \) is absolutely convergent, then \( \sum_{k=1}^{\infty} a_k \) converges. A counterexample is proposed where \( a_k = -1 \) and \( b_k = 0 \), demonstrating that while \( b_k \) is absolutely convergent, \( \sum_{k=1}^{\infty} a_k \) diverges. This confirms that the statement is false under certain conditions.

PREREQUISITES
  • Understanding of sequences and series in mathematics
  • Familiarity with the concept of absolute convergence
  • Knowledge of counterexamples in mathematical proofs
  • Basic proficiency in mathematical notation and inequalities
NEXT STEPS
  • Study the properties of absolutely convergent series in detail
  • Explore the implications of counterexamples in mathematical proofs
  • Learn about the comparison test for series convergence
  • Investigate the relationship between convergence and divergence in sequences
USEFUL FOR

Mathematics students, educators, and anyone studying series convergence, particularly those interested in advanced calculus or real analysis.

DEMJ
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Homework Statement



if a_k \le b_k for all k \in \mathbb{N} and \sum_{k=1}^{\infty} b_k is absolutely convergent, then \sum_{k=1}^{\infty} a_k converges.



Homework Equations


It's either true or false.


The Attempt at a Solution


I think a counterexample to prove it's false is if we let a_k=-1, b_k = 0 which satisfies a_k \le b_k and b_k is abs. convergent but \sum_{k=1}^{\infty} a_k diverges.
Is this a correct counterexample?
 
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that looks reasonable, if the ak & bk were positive numbers or it was written for maginutudes it would be true
 

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