Find the interval of convergence of (x^n)/(n +1)

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SUMMARY

The discussion focuses on finding the interval of convergence for the series represented by (x^n)/(n + 1). The user initially applies the ratio test, leading to the limit expression lim (x(n! + 1))/((n + 1)! + 1) as n approaches infinity. The conclusion drawn is that the limit equals 0, suggesting an interval of convergence from -∞ to ∞, with a radius of convergence of ∞. However, the importance of rigorous proof rather than assumption is emphasized, particularly in handling factorials.

PREREQUISITES
  • Understanding of series convergence tests, specifically the ratio test.
  • Familiarity with factorial notation and properties, particularly n!.
  • Knowledge of limits and their application in calculus.
  • Basic concepts of power series and their intervals of convergence.
NEXT STEPS
  • Study the application of the ratio test in detail, focusing on factorials.
  • Learn about the properties of power series and how to determine their convergence.
  • Explore alternative convergence tests, such as the root test and comparison test.
  • Practice solving similar problems involving series and convergence intervals.
USEFUL FOR

Students studying calculus, particularly those focusing on series and convergence, as well as educators seeking to clarify the application of convergence tests in mathematical analysis.

Painguy
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Homework Statement


My main issue here is that if I use the ratio test I end up with lim (x(n!+1))/((n+1)!+1) n-> ∞

I don't know how to progress here. I believe that the limit will equal 0 and so it's interval of convergence is from -∞<x<∞ with a Radius of convergence of ∞. Is it safe for me to assume that?

Homework Equations





The Attempt at a Solution

 
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It is never safe to assume anything. Prove it.

ehild
 
ehild said:
It is never safe to assume anything. Prove it.

ehild

Well that's why I was asking. I'm not sure how to deal with the factorials here.
 
Well, do you know what n! is?

ehild
 

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