Is This a Correct Definition of a Limit in Calculus?

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Discussion Overview

The discussion revolves around the definition of a limit in calculus, specifically questioning the validity of a proposed statement regarding the relationship between the variables involved in the limit definition. Participants explore examples and hints to clarify the concept.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant suggests demonstrating that the statement "for all d>0 there exists e>0 such that 0<|x-a| |f(x)-L|
  • Another participant proposes setting e to 2 as a potential solution to the problem, implying that this could satisfy the condition.
  • A third participant expresses confusion about the hint regarding setting e to 2, noting the importance of the phrase "there exists e."
  • One participant points out that if e can be set to 2, then the clause "there exists e" is indeed satisfied, suggesting that the definition may not be as restrictive as implied.
  • Another participant questions the ability to answer the original question without a clear definition of a limit, suggesting that a more meaningful approach would involve providing the definition and then examining a specific function that meets one definition but not the other.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the validity of the proposed definition of a limit, with multiple viewpoints and interpretations presented throughout the discussion.

Contextual Notes

Some participants highlight the need for a clear definition of a limit to engage meaningfully with the problem, indicating that the discussion may lack sufficient context for a thorough analysis.

flying2000
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show by example that the stament
for all d>0 there exists e>0 such that o<|x-a|<d ->
|f(x)-L|<e is Not the definition of limit.

would somebody give me a hint?
 
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Why not let e be 2?
 
I don't understand..

matt grime said:
Why not let e be 2?
I think it's "there exists e"
 
I take it that means you didn't understand the hint?

Ok, the function f(x)=2 for all x in R is obvioulsy continuous. Take your known incorrect definition, take my hint and think...
 
"there exists e"

If you can do it by setting e = 2, then this clause is certainly satisfied.
 
how can you answer this without a definition of limit? a more meaningful question would be to also give the definition of limit and then ask for a function and number that satisfies one definition and not the other.
 

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