Is the Limit of Powers Equal to the Power of Limits?

  • Context: Undergrad 
  • Thread starter Thread starter sutupidmath
  • Start date Start date
  • Tags Tags
    Limit
Click For Summary

Discussion Overview

The discussion revolves around the mathematical expression involving limits and powers, specifically whether the limit of a power can be equated to the power of a limit. Participants explore the continuity of functions and seek clarification on theorems that support this relationship.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether the limit of the expression (a^x_n)^x'_n as n approaches infinity is equal to (a^lim x_n)^lim x'_n.
  • Another participant asserts that the equality holds due to the continuity of the exponential function.
  • A further inquiry is made about the existence of a theorem or definition that generalizes this relationship.
  • Some participants reference the definition of continuity, suggesting that it supports the transition between the two expressions.
  • One participant proposes the squeeze theorem as a potential relevant concept.
  • There is a reiteration of the definition of continuity, emphasizing that it implies the limit of a function at a point equals the function's value at that point.
  • A participant expresses a desire for a specific theorem that encapsulates the discussed concepts, indicating a lack of such references in their calculus materials.

Areas of Agreement / Disagreement

Participants generally agree on the relevance of continuity to the discussion, but there is no consensus on the existence of a specific theorem that formalizes the relationship between the limits and powers as posed in the original question.

Contextual Notes

Some participants express uncertainty regarding the formalization of the concepts discussed, particularly in relation to theorems that may not be covered in standard calculus texts.

sutupidmath
Messages
1,629
Reaction score
4
i need someone to coment on this:

lim(a^x_n)^x'_n, when n->infinity = (a^lim x_n)^lim x'_n , n-> infinity,

what i am asking here is if we can go from the first to the second? or if these two expressions are equal??

any help??
 
Physics news on Phys.org
Yes, because the exponential function, ax, is continuous.
 
one more thing here. Is there a theorem or a deffinition that supports similar expressions in a more generalized way?? i forgot to mention this also
 
I'm not sure what you mean. I was referring to the general fact that, from the definition of "continuous", if xn is a sequence of numbers converging to a and f is a function continuous at a, then
\lim_{n \rightarrow \infnty} f(x_n)= f(\lim_{n\rightarrow \infty} x_n)= f(a)
 
HallsofIvy said:
I'm not sure what you mean. I was referring to the general fact that, from the definition of "continuous", if xn is a sequence of numbers converging to a and f is a function continuous at a, then
\lim_{n \rightarrow \infnty} f(x_n)= f(\lim_{n\rightarrow \infty} x_n)= f(a)


yeah this is what i am asking. But what i want to know is if there is a theorem that states this, what you wrote. Or how do we know that this is so?
 
Maybe the squeeze theorem?

glenn
 
As Halls indicated, it's essentially the definition of continuity. The definition of continuity for a function f of one real variable defined on an interval (a,b) is for any x in (a,b),

\lim_{y \rightarrow x} f(y) = f(x)

(ie. the limit exists and is equal to f(x))
 
Data said:
As Halls indicated, it's essentially the definition of continuity. The definition of continuity for a function f of one real variable defined on an interval (a,b) is for any x in (a,b),

\lim_{y \rightarrow x} f(y) = f(x)

(ie. the limit exists and is equal to f(x))


Yeah, i know the definition of continuity, i was just wondering if there is a specific theorem that states this, as i have not encountered one on my calculus book. However, i do understand it now.
Many thanks to all of you.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 16 ·
Replies
16
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K