What Happens When You Calculate One to the Infinity Power?

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Discussion Overview

The discussion revolves around the mathematical expression of one raised to the infinity power, particularly in the context of limits and indeterminate forms. Participants explore the implications of this expression within the framework of a defined function and its behavior as a parameter approaches zero.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant questions the outcome of evaluating \(1^{\infty}\) and expresses uncertainty about whether it equals 1, based on their calculator's output.
  • Another participant asserts that multiplying 1 by itself infinitely results in 1, suggesting that it should converge to 1.
  • A different participant states that \(1^{\infty}\) is undefined, indicating a need for further analysis.
  • One participant provides a limit analysis for the function \(f(p) = ((a^p + b^p)/2)^{(1/p)}\) and suggests that if \(a = b\), the limit is simply \(a\). They also explore the case when \(a\) is greater than \(b\) and rewrite the expression to analyze its behavior as \(p\) approaches 0.
  • Another participant emphasizes that \(1^{\infty}\) is an indeterminate form and that further analysis is required, proposing an approximation method for evaluating the limit as \(p\) approaches 0.
  • A hint is provided to consider the limit of a related sequence \(g(p) = \log f\) to utilize properties of continuity in the analysis.

Areas of Agreement / Disagreement

Participants express differing views on the nature of \(1^{\infty}\), with some asserting it equals 1 and others stating it is undefined. The discussion remains unresolved as participants explore various mathematical approaches and interpretations.

Contextual Notes

Participants note that \(1^{\infty}\) is an indeterminate form, which introduces complexity in evaluating limits. The analysis relies on approximations and the behavior of the function as parameters approach specific values, indicating potential limitations in the assumptions made.

arpitm08
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one raised to the infinity power help please!

Let a and b be positive real numbers. For real number p define, f(p) = ((a^p + b^p)/2)^(1/p). Evaluate the limit of f(p) as p approaches 0.

By directly plugging in zero, you would get (1)^inf. Wouldn't that equal 1 or would it be something else? When I put it into my 89 i got 1 as my answer, but for some reason I don't think that it is right. Please help!
 
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why wouldn't it? 1x1x1x1... is still 1 isn't it?

you can also check the graph at 0 to see if it converges to 1 when you plug in positive real numbers for a and b. don't the 89s take limits?
 


00PS said:
why wouldn't it? 1x1x1x1... is still 1 isn't it?

?
1^{\infty} is undefined!
 


If a=b, note that the limit is "a".

Let then "a" be greater than "b", and rewrite:
(\frac{(a^{p}+b^{p}}{2})^{\frac{1}{p}}=\frac{a}{2^{\frac{1}{p}}}({1+\frac{1}{N})^{\frac{1}{p}}, \frac{1}{N}=(\frac{b}{a})^{p}
Then,
\frac{1}{p}=N\frac{\ln(\frac{a}{b})}{N\ln(N)}


Therefore, you may rewrite this as:
((1+\frac{1}{N})^{N})^{\frac{\ln(\frac{a}{b})}{N\ln(N}}}
which remains nasty..
 
Last edited:


"If a=b, note that the limit is "a"."
Indeed.
"Wouldn't that equal 1"
No.
That is what is called an indeterminite form.
further analysis is needed.
f(p)=((a^p + b^p)/2)^(1/p)
Let us consider an approximation that is exact in the limit.
a^p~1+p log(a)
b^p~1+p log(b)
if p~0
thus
(a^p + b^p)/2~1+p log sqrt(ab)
if p~0
(1+x)^(1/P)~exp(x/p)
if p~0 and x~0

by combining these the answer should be clear.
 


Hint: if your sequence is f(p), consider the limit of the related sequence g(p) where g=\log f. Then use some standard properties of continuity.
 

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