Help with alternating series sum

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SUMMARY

The discussion focuses on finding the sum of the alternating series 1 - e + e²/2! - e³/3! + e⁴/4! + ... The solution involves recognizing that this series can be expressed using the MacLaurin series for e^x by substituting x with -e. The user initially attempted to apply the Ratio Test but found it unhelpful. Ultimately, the correct approach was identified, confirming that substituting x = -e yields the desired alternating series.

PREREQUISITES
  • Understanding of MacLaurin series
  • Familiarity with the exponential function e^x
  • Knowledge of factorial notation and its application in series
  • Basic concepts of convergence tests, specifically the Ratio Test
NEXT STEPS
  • Study the properties of MacLaurin series in-depth
  • Learn about the convergence of alternating series
  • Explore the application of the Ratio Test in various contexts
  • Investigate other series expansions for functions beyond e^x
USEFUL FOR

Students studying calculus, particularly those focusing on series and sequences, as well as educators looking for examples of series manipulation and convergence tests.

Abyssnight
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Homework Statement



Given the following: 1 - e + e2/2! - e3/3! + e4/4! + ...
Find the sum of series

Homework Equations



The MacLaurin equation for ex

The Attempt at a Solution



Well I thought that it would look like \sum(-1)^n\frac{e^n}{n!}
Tried the Ration Test and got no where. So I'm just kind of stumped
 
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Consider the MacLaurin series for ex.

ex = 1 + x + x2/2! + x3/3! + x4/4! ...

Now, what do you think you need to put into x to get the alternate series in your question?
 
Wow, haha. I must have had a long night to for some reason miss the obvious. x = -e and it works. Thank you haha.
 

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