How Can You Simplify the Process of Calculating Partial Sums?

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Discussion Overview

The discussion revolves around methods for simplifying the calculation of partial sums, particularly in the context of infinite series. Participants explore whether there are general formulas or techniques that can be applied to streamline the process of obtaining partial sums, with a specific example provided for illustration.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about easier methods for calculating partial sums beyond direct addition, referencing a specific formula involving integrals.
  • Another participant points out the lack of definition for the terms in the sum, suggesting that without this information, no simplification can be proposed.
  • A subsequent reply reiterates the need for defined terms in the sum to explore potential simplifications.
  • A participant provides a specific example of an infinite series, \(\sum^{\infty}_{n=0} \frac{(-1)^{n}x^{2n}}{n!}\), suggesting that there may be general formulas applicable.
  • In response to the example, another participant states that for this specific series, the sum equals \(\exp(-x^2)\), but asserts that partial sums can only be obtained through direct addition.

Areas of Agreement / Disagreement

Participants generally agree that the definition of terms in the sum is crucial for discussing simplification methods. However, there is disagreement regarding the applicability of general formulas for calculating partial sums, as one participant believes such formulas exist while another insists on the necessity of direct addition for the specific example provided.

Contextual Notes

The discussion highlights the importance of defining terms in mathematical expressions and the limitations of generalizing methods for calculating partial sums without specific context. The reliance on direct addition for certain series is noted, but the potential for broader techniques remains unresolved.

Stratosphere
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Is there a particular way to get the partial sum easier than just adding the terms up?

In this formula it would take a while to add up the terms if I wanted to use n=20:

[tex]S_{n}+\int ^{\infty}_{n+1}f(x) dx\leqs\leq S_{n}+\int ^{\infty}_{n}f(x)dx[/tex]

How would I get the exact value of the sum?
 
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You haven't defined what the terms in the sum are, so there is no way of knowing what can be done.
 
mathman said:
You haven't defined what the terms in the sum are, so there is no way of knowing what can be done.

Oh, I though that there was something like a formula that could be used in general cases. So I'll use the example:

[tex]\sum^{\infty}_{n=0} \frac{(-1)^{n}x^{2n}}{n!}[/tex]
 
For the particular example the sum is exp(-x2). For this case, there is no way to get partial sums except by direct addition.
 

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