Finding Alternative Representations for the Convergent Series Ʃ ((-1)^(i-1))/i

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Homework Help Overview

The discussion revolves around the series Ʃ ((-1)^(i-1))/i, which is known to converge to ln(2). The original poster seeks alternative representations for this series, particularly in forms that might include quadratic terms or other series types.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants explore the possibility of representing the series in different forms, including questioning the use of Taylor series expansions. There is also a request for clarification regarding the nature of the alternative representations being sought, particularly concerning quadratic terms.

Discussion Status

The discussion is ongoing, with participants providing suggestions and seeking clarification on the original poster's intent. Some guidance has been offered regarding the expansion of ln(1+x) as a Taylor series, but there is no explicit consensus on the best approach to represent the series in question.

Contextual Notes

The original poster notes that their calculus textbook does not provide information beyond the convergence of the series, indicating a potential gap in resources for exploring alternative representations.

venom192
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Homework Statement



I basically need to know if the series Ʃ ((-1)^(i-1))/i can be represented in other ways (e.g. a Taylor series, but I doubt it). I know it converges to ln2, but I need to know if there's a series like x^2, x^4, ... or something like it that I can represent the series with.

Homework Equations



Ʃ ((-1)^(i-1))/i for i=1 to q, where q is a finite, but very large number

The Attempt at a Solution



My calc textbook doesn't examine that series for anything besides its convergent nature, and I can't find any online resources for it. Any help would be appreciated.
 
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I'm not sure if I understand what you are asking... But have you tried expanding ln(1+x) as a Taylor series?
 
clamtrox said:
I'm not sure if I understand what you are asking... But have you tried expanding ln(1+x) as a Taylor series?

Thanks for the reply. This question specifically pertains to the series I asked about - I was just using the Taylor series as a possibility of an alternate representation of the series. After looking at my old calc textbook, I see that I was way off base suggesting a Taylor series.

I'll rephrase this - Is it possible to rewrite the series Ʃ(-1^i)/i as another type of series that contains a quadratic term?
 
Quadratic in what? You can of course develop the series at different points. If you solve for the series of ln (3/2+x) then you'll end up with series containing powers of 1/2.
 

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