Is it possible for radius of convergence to be negative?

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Discussion Overview

The discussion revolves around the concept of the radius of convergence in mathematical series, specifically questioning whether it can be negative. Participants explore the implications of a negative radius of convergence and reference definitions from calculus.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions if the radius of convergence "R" can be negative, providing an example of the inequality -|x| < 1 and suggesting R = -1.
  • Another participant prompts a look at the definition of radius of convergence to clarify the question.
  • A repeated concern is raised regarding the usefulness of the statement if -|x| < 1 allows for any number, implying that the example may not be meaningful.
  • A further suggestion is made to consult a calculus textbook for the formal definition of radius of convergence.

Areas of Agreement / Disagreement

The discussion does not reach a consensus, as participants express differing views on the validity and implications of a negative radius of convergence.

Contextual Notes

Participants reference definitions and examples but do not resolve the implications of a negative radius of convergence or clarify the conditions under which the radius is defined.

jkh4
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is it possible for "R" (radius of convergence) to be negative?

is it possible for "R" (radius of convergence) to be negative?

for example: -|x|<1 and R=-1?
 
Last edited:
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What does the definition say?
 
jkh4 said:
is it possible for "R" (radius of convergence) to be negative?

for example: -|x|<1 and R=-1?

If -|x|< 1,then x can be any number. So it's not a very useful thing to say
 
As Hurkyl said, take any Calculus book and look up the definition of "radius of convergence"!
 

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