Limit of monotic transformation

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Discussion Overview

The discussion revolves around the properties of limits in the context of monotonic transformations of functions. Participants explore whether the limit of a monotonic transformation of a function is equivalent to the monotonic transformation of the limit of that function, specifically addressing the conditions under which this holds true.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions if the limit of a monotonic transformation can be expressed as \(\lim_{x \rightarrow a} f(g(x)) = f(\lim_{x \rightarrow a} g(x))\) under certain conditions.
  • Another participant points out that the original equation lacks clarity regarding the dependence on \(n\), suggesting a need for clearer notation.
  • A subsequent post corrects the notation from \(n\) to \(x\) to clarify the intended limit expression.
  • One participant asserts that continuity of \(f\) at \(g(a)\) is necessary for the limit equality to hold, indicating that \(g(x)\) may not be relevant to the limit itself.
  • There is a suggestion to simplify the consideration to \(\lim_{x \rightarrow a} f(x) = f(a)\) instead of involving \(g(x)\).

Areas of Agreement / Disagreement

Participants express differing views on the necessity of continuity for the limit equality to hold, indicating that the discussion remains unresolved regarding the conditions required for the proposed limit relationship.

Contextual Notes

There are unresolved assumptions about the continuity of the functions involved and the specific behavior of \(g(x)\) as \(x\) approaches \(a\). The discussion does not clarify the implications of monotonicity on the limit properties.

tunaaa
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Hello, I was just wondering if is it true that the limit of a monotonic transformation of a function is the same as the monotonic transformation of its limit? That is, does

[tex]\lim_{n \rightarrow a} f(g(x)) = f(\lim_{n \rightarrow a} g(x))[/tex]

for monotonic [tex]f[/tex], some [tex]a[/tex], and such that if the limit does not exist for one side of the expression, it doesn't exist for both?

Thanks.
 
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Your original equation does not describe the dependence on n of anything.
 
Sorry, replace n with x - was very tired!
 
Correction: [tex]\lim_{x \rightarrow a} f(g(x)) = f(\lim_{x \rightarrow a} g(x))[/tex]
 
I believe you need f to be continuous at g(a). The g(x) may be a red herring. Just look at lim(x->a)f(x)=f(a).
 

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