How to Use Integration and Derivatives to Find the Sum of a Series

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Homework Help Overview

The discussion revolves around the use of integration and derivatives to find the sum of a series involving the terms (x^(2n-1))/(2n-1). Participants are exploring the connection between Taylor series and the series in question.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to manipulate the Taylor series for 1/(1-x) and substitute x^2 for x to relate it to their series. They express uncertainty about how to use integration or differentiation to achieve the desired format for their series.
  • Some participants suggest changing the limits of summation and modifying the terms to facilitate the manipulation of the series.
  • There is a discussion about the validity of changing the index of summation and how it affects the series representation.

Discussion Status

Participants are actively engaging with the problem, with some offering hints and affirmations regarding the original poster's approach. There is a sense of exploration as they navigate through the series transformations and the implications of their manipulations.

Contextual Notes

Participants are working under the constraints of using Taylor series and are considering the implications of changing summation indices. The original poster notes the transition from n=1 to n=0 and the adjustments made to the series terms.

Dell
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Σ (x2n-1)/(2n-1)
n=1

what i tried to do was take the taylor series:


Σ (xn)=1/(1-x)
n=1

so i can substitute x2 for x


Σ (x2n)=1/(1-x2)
n=1


now i need to to use some form of integration/derivative to get to my series from the taylor series,
my problem is that integral will give me x2n+1/(2n+1) , and derivative will give me 2n*x2n-1, but i need the format of the integration- a division format- but the numberss from the derivative- 2n-1 -
 
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Hint: Change the limits to n = 0 to ∞ and (2n - 1) to (2n + 1).
 
tell me if this is right


Σ x2n-1/(2n-1)
n=1
=

Σ x2(n+1)-1/(2(n+1)-1)
n=0
=

Σ x2n+1/(2n+1)
n=0

fx= 1/(1-x) = Σ xn
x==>x2
fx= 1/(1-x2) = Σ x2n

[tex]\int[/tex]fx=[tex]\int[/tex]1/(1-x2)=[tex]\int[/tex]Σ x2n

0.5*ln|(1+x)/(1-x)| = x2n+1/2n+1

and i can do all of this because i say n=1, and n*=0, therefore n* goes from 0-∞ and n goes from 1-∞, making n*=n+1 so i can use the same taylor series, but instead of n, i write n+1
 
Ya looks good.
 

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