Limits of Sequences .... Stoll Theorem 2.2.6

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Discussion Overview

The discussion revolves around the proof of parts (a) and (b) of Theorem 2.2.6 from Manfred Stoll's "Introduction to Real Analysis," specifically focusing on the limits of certain special sequences. Participants are seeking assistance in understanding and constructing a proof for part (a).

Discussion Character

  • Homework-related, Mathematical reasoning, Exploratory

Main Points Raised

  • One participant expresses difficulty in starting the proof for part (a) of Theorem 2.2.6 and requests help.
  • Another participant proposes a solution involving the limit of a sequence, stating that for any $$\epsilon > 0$$, the inequality $$\left\lvert\frac{1}{ n^p } - 0\right\rvert < \epsilon$$ leads to $$n > \frac{1}{ \epsilon^{ \frac{1}{ p } }}$$.
  • This proposed solution is affirmed by another participant, who confirms the reasoning and expresses confidence in the approach.
  • A follow-up question is raised regarding the axioms, theorems, or definitions of real numbers that are used in the transition from $$\frac{1}{ n^p } < \epsilon$$ to $$n > \frac{1}{ \epsilon^{ \frac{1}{ p } }}$$.

Areas of Agreement / Disagreement

There is some agreement on the proposed solution, as it receives confirmation from other participants. However, the discussion regarding the underlying axioms or definitions indicates that not all aspects of the proof are settled, and further clarification is sought.

Contextual Notes

The discussion includes references to specific mathematical inequalities and limits, but does not resolve the foundational aspects related to the axioms or definitions of real numbers that are necessary for the proof.

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In his book: Introduction to Real Analysis, Manfred Stoll does not prove parts (a) and (b) of Theorem 2.2.6 on the limits to certain special sequences ...

I am having trouble getting started on the proof of part (a) ... can someone please help me to make a meaningful start to the proof ... (despite the fact that Stoll informs us that the proof is straightforward ... :( ... )

Theorem 2.2.6 reads as follows:

View attachment 7194Peter
 
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Peter said:
In his book: Introduction to Real Analysis, Manfred Stoll does not prove parts (a) and (b) of Theorem 2.2.6 on the limits to certain special sequences ...

I am having trouble getting started on the proof of part (a) ... can someone please help me to make a meaningful start to the proof ... (despite the fact that Stoll informs us that the proof is straightforward ... :( ... )

Theorem 2.2.6 reads as follows:

Peter

After some reflection I have a proposed solution ...To show $$\text{lim}_{ n \rightarrow \infty } = 0$$ Now ... for any $$\epsilon \gt 0$$ the inequality $$\left\lvert\frac{1}{ n^p } - 0\right\rvert \lt \epsilon$$gives $$\frac{1}{ n^p } \lt \epsilon$$ or $$n \gt \frac{1}{ \epsilon^{ \frac{1}{ p } }}$$ ... ... Hence ... if we take $$N \gt \frac{1}{ \epsilon^{ \frac{1}{ p } } } $$ ... then for $$n \gt N$$ we have ...$$\frac{1}{ n^p } \lt \left(\frac{1}{ \frac{1}{ \epsilon^{ \frac{1}{p} } } }\right)^p = \epsilon $$Is that correct?

Peter
 
Last edited:
Peter said:
After some reflection I have a proposed solution ...To show $$\text{lim}_{ n \rightarrow \infty } = 0$$ Now ... for any $$\epsilon \gt 0$$ the inequality $$\left\lvert\frac{1}{ n^p } - 0\right\rvert \lt \epsilon$$gives $$\frac{1}{ n^p } \lt \epsilon$$ or $$n \gt \frac{1}{ \epsilon^{ \frac{1}{ p } }}$$ ... ... Hence ... if we take $$N \gt \frac{1}{ \epsilon^{ \frac{1}{ p } } } $$ ... then for $$n \gt N$$ we have ...$$\frac{1}{ n^p } \lt \left(\frac{1}{ \frac{1}{ \epsilon^{ \frac{1}{p} } } }\right)^p = \epsilon $$Is that correct?

Peter
Yes! (Yes)
 
Opalg said:
Yes! (Yes)
Thanks Opalg ... it gives me great confidence when you or Evgeny confirm my effort ...

Thank you ...

Peter
 
Peter said:
After some reflection I have a proposed solution ...To show $$\text{lim}_{ n \rightarrow \infty } = 0$$ Now ... for any $$\epsilon \gt 0$$ the inequality $$\left\lvert\frac{1}{ n^p } - 0\right\rvert \lt \epsilon$$gives $$\frac{1}{ n^p } \lt \epsilon$$ or $$n \gt \frac{1}{ \epsilon^{ \frac{1}{ p } }}$$ ... ... Hence ... if we take $$N \gt \frac{1}{ \epsilon^{ \frac{1}{ p } } } $$ ... then for $$n \gt N$$ we have ...$$\frac{1}{ n^p } \lt \left(\frac{1}{ \frac{1}{ \epsilon^{ \frac{1}{p} } } }\right)^p = \epsilon $$Is that correct?

Peter

In going from: $$\frac{1}{ n^p } \lt \epsilon$$ to

$$n \gt \frac{1}{ \epsilon^{ \frac{1}{ p } }}$$

What are the axioms or theorems or definitions of the real Nos that you use??
 

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