Discover the Sum of a Series: Find the Value with Expert Help

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Homework Help Overview

The discussion revolves around finding the value of an infinite series that alternates between positive and negative fractions. The series is expressed as 1 + 1/2 - 1/3 - 1/4 + 1/5 + 1/6 - 1/7 - 1/8 + ... and falls within the subject area of calculus, specifically series and convergence.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants have expressed their struggles with the problem, questioning the feasibility of finding the sum. Some suggest splitting the series into two alternating series, while others discuss the implications of rearranging terms based on Riemann's Alternating Series Theorem and the Leibniz Series Theorem.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the series and its properties. Some guidance has been offered regarding textbook references and hints about the nature of the series, but no consensus has been reached on a specific method or solution.

Contextual Notes

Participants are reminded of forum rules regarding effort in problem-solving, and there is an acknowledgment of the complexity of the series, particularly in its natural form versus potential rearrangements.

mathlover1
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Find the value of sum

[tex]1+\frac{1}{2}-\frac{1}{3}-\frac{1}{4}+\frac{1}{5}+\frac{1}{6}-\frac{1}{7}-\frac{1}{8}+...[/tex]
 
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Mark44 said:
What have you tried?
it seems so impossible to do!
 


Per the forum rules, you need to show some effort at trying to solve a problem you post.
 


mathlover1 said:
Find the value of sum

[tex]1+\frac{1}{2}-\frac{1}{3}-\frac{1}{4}+\frac{1}{5}+\frac{1}{6}-\frac{1}{7}-\frac{1}{8}+...[/tex]

mathlover,

While I am not allowed to show you how fo find the sum of the series because the old men here would have me booted of the forum but here are a legal hint ;)

Since you have trouble with this I guess you are a first semester student. Look in your Calculus textbook under series and search for the paragraph which deals the series where there is change from plus to minus and back of the series elements ;)

When you have found the right paragragh it will allow you to conclude which kind of series this is then report back :) Because then you will be able to find the sum the very easily ;)
 


Try to split the series into two alternating series. Can you sum either one?
 


a little warning :)

this series could be summed to any desired value if you change the places of the parts (Riemann's Alternating Series Theorem).

in its natural form you can estimate the sum using Liebnitz Series Theorem (Alternating Series).
 
Last edited:


gomunkul51 said:
a little warning :)

this series could be summed to any desired value if you change the places of the parts (Riemann's Alternating Series Theorem).

in its natural form you can estimate the sum using Liebnitz Series Theorem (Alternating Series).
As given, this series is not an alternating series.
 


May be you right, but:

it is the sum of two alternating series':

sum((-1)^n/2n+1) + sum((-1)^n/2n+2)

and each obeys the rules of an alternating series, and everything I said if valid.
 
  • #10


gomunkul51 said:
May be you right, but:

it is the sum of two alternating series':

sum((-1)^n/2n+1) + sum((-1)^n/2n+2)

and each obeys the rules of an alternating series, and everything I said if valid.

Sure. And you can EXACTLY sum the original series if you can sum each of those.
 

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