Does the Tail of a Convergent Series Also Converge to Zero?

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Discussion Overview

The discussion revolves around the convergence of a series and whether the tail of a convergent series also converges to zero. Participants explore the implications of series convergence, mathematical definitions, and the relationship between the full series and its tail.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant asserts that if the series {\displaystyle \sum_{n=1}^{\infty}a_{n}} converges, then for any natural number N, the tail {\displaystyle \sum_{n=N+1}^{\infty}a_{n}} also converges, suggesting that the limit approaches zero as N approaches infinity.
  • Another participant asks for clarification on how to express the difference between the full series and the tail as a sum, indicating a need for further mathematical manipulation.
  • A third participant reiterates the convergence of both the full series and the tail, questioning the definition of convergence and whether this is a homework problem.
  • One participant claims that since the difference between a full series and its tail is finite, the convergence properties should be the same for both.

Areas of Agreement / Disagreement

Participants express varying degrees of understanding regarding the convergence of series and their tails. There is no clear consensus on the implications of convergence or the definitions involved, indicating that multiple views remain in the discussion.

Contextual Notes

Some participants reference mathematical definitions and properties of convergence without fully resolving the implications or assumptions underlying their claims. The discussion includes questions about whether it constitutes a homework problem, which may affect the context of the inquiry.

Who May Find This Useful

This discussion may be useful for students and individuals interested in series convergence, mathematical proofs, and those seeking clarification on related concepts in analysis.

DaniV
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{\displaystyle \sum_{n=1}^{\infty}a_{n}}
is converage, For N\in
\mathbb{N}\sum_{n=N+1}^{\infty}an
is also converage

proof that \lim_{N\rightarrow\infty}(\sum_{n=N+1}^{\infty}an)=0
Code:
{\displaystyle \sum_{n=1}^{\infty}a_{n}}
  is converage, For N\in
\mathbb{N}

\sum_{n=N+1}^{\infty}an
  is also converage

proof that \lim_{N\rightarrow\infty}(\sum_{n=N+1}^{\infty}an)=0
 
Last edited:
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Can you write Σ1an - ΣN+1an as a sum?

It might be helpful to put Σ1an = c .
 
DaniV said:
{\displaystyle \sum_{n=1}^{\infty}a_{n}}
is converage, For N\in
\mathbb{N}\sum_{n=N+1}^{\infty}an
is also converage

proof that \lim_{N\rightarrow\infty}(\sum_{n=N+1}^{\infty}an)=0
Please take a look at our LaTeX tutorial -- https://www.physicsforums.com/help/latexhelp/
I believe this is what you were trying to convey:
##\sum_{n=1}^{\infty}a_{n}## converges.

For ##N \in \mathbb{N}, \sum_{n = N+1}^{\infty}a_n## also converges.

What does it mean for a series to converge? How is this defined?

Also, is this a homework problem?
 
The difference between a full series and a tail is finite, so convergence is te same for both.
 

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