Prove Limit Rule: Learn the Constant Concept

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Discussion Overview

The discussion centers around proving that the limit of a constant function equals the constant itself. Participants explore the definition of limits and engage in a technical examination of the proof process, with a focus on the epsilon-delta definition of limits.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant expresses interest in proving that the limit of a constant function is the constant itself and requests links for assistance.
  • Another participant provides a link to a resource on limit proofs but suggests that the original poster should search for information in the future.
  • A participant reiterates that proving this limit is straightforward and suggests using the epsilon-delta definition to demonstrate that for a constant function f(x) = k, the condition |f(x) - f(a)| < ε holds when |x - a| < δ.
  • Further clarification is sought regarding the application of the epsilon-delta definition, specifically whether one can specify a δ for a given ε to satisfy the limit condition.

Areas of Agreement / Disagreement

Participants generally agree that the limit of a constant function can be proven using the epsilon-delta definition, but there is no consensus on the completeness of the proof or the necessary steps involved.

Contextual Notes

The discussion includes assumptions about the understanding of the epsilon-delta definition of limits and does not resolve whether the proposed proof steps are sufficient or accurate.

shihab-kol
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Hello, I would like to begin by saying that this does not fall into any homework or course work for me. It is just my interest.
I need to prove that limit of a constant gives the constant it self. Can some one provide a link? I have exams or I would have searched myself but unfortunately I don't have time. So, I had to post this thread.
 
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shihab-kol said:
Hello, I would like to begin by saying that this does not fall into any homework or course work for me. It is just my interest.
This is one of the easiest of limits to prove, using the definition of a limit to prove it. If f(x) = k, a constant, can you show that ##|f(x) - f(a)| < \epsilon## when ##|x - a| < \delta##?
 
Mark44 said:
This is one of the easiest of limits to prove, using the definition of a limit to prove it. If f(x) = k, a constant, can you show that ##|f(x) - f(a)| < \epsilon## when ##|x - a| < \delta##?
If I take f(a) =k for some interval around x , then |f(x) - f(a)| =0 <E since by definition E >0.
But will this work?
 
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shihab-kol said:
If I take f(a) =k for some interval around x , then |f(x) - f(a)| =0 <E since by definition E >0.
But will this work?
It will work, but you need to say more.
Someone gives you a value of ##\epsilon > 0##. Can you specify a number ##\delta > 0## so that when ##|x - a| < \delta##, then ##|f(x) - f(a)| < \epsilon##?
 
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