Limit of ln^2(x-2) as x approaches 3: Solving the Result

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Homework Help Overview

The discussion revolves around evaluating the limit of the expression {ln^2(x-2)}^(x-3) as x approaches 3. Participants are exploring the continuity of the function and the implications of substituting x=3 directly into the expression.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Some participants discuss the continuity of the expression and the challenges of direct substitution at x=3, particularly the indeterminate form 0^0. Others suggest using l'Hôpital's rule to evaluate the limit and clarify the manipulation of logarithmic expressions.

Discussion Status

Participants are actively engaging with the problem, questioning the validity of direct substitution and exploring alternative methods such as l'Hôpital's rule. There is a mix of interpretations regarding the manipulation of logarithmic terms, with some seeking clarification on the equivalence of different expressions.

Contextual Notes

There are indications of confusion regarding the notation used for logarithmic functions, specifically the distinction between ln^2(x-2) and (ln(x-2))^2. The discussion reflects an ongoing exploration of these definitions and their implications for the limit evaluation.

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hi, i want to ask help to solved my task.
if limit approach 3 of {ln^2(x-2)}^(x-3), how is the result?
thanks before
 
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[STRIKE]As it's written, {ln^2(x-2)}^(x-3) is continuous for x>2, so you can just plug in x=3 to get the limit. Is that exactly what the original expression was?[/STRIKE]
 
Last edited:
Bohrok said:
As it's written, {ln^2(x-2)}^(x-3) is continuous for x>2, so you can just plug in x=3 to get the limit. Is that exactly what the original expression was?

no i cannot.
if i plug in x=3, so it will be {ln^2(3-2)}^(3-3) = {ln^2 1}^0 = 0^0 (unconditional)...
 
Sorry about the last post, I had something else in mind when I wrote that.

(ln2(x - 2))x-3 = (ln(x - 2))2(x-3), so

(\ln^2(x - 2))^{x-3} = e^{\ln(\ln(x-2))^{2(x-3)}} = e^{2(x-3)\ln(\ln(x-2))} = e^{2\cdot\frac{\ln(\ln(x-2))}{\frac{1}{x-3}}
and
\lim_{x\rightarrow 3}(\ln^2(x - 2))^{x-3} = e^{2\lim_{x\rightarrow 3}\frac{\ln(\ln(x-2))}{\frac{1}{x-3}}

Now what you want to do is use l'Hôpital's rule to find that last limit.
 
Last edited:
Bohrok said:
Sorry about the last post, I had something else in mind when I wrote that.

(ln2(x - 2))x-3 = (ln(x - 2))2(x-3), so

(\ln^2(x - 2))^{x-3} = e^{\ln(\ln(x-2))^{2(x-3)}} = e^{2(x-3)\ln(\ln(x-2))} = e^{2\cdot\frac{\ln(\ln(x-2))}{\frac{1}{x-3}}
and
\lim_{x\rightarrow 3}(\ln^2(x - 2))^{x-3} = e^{2\lim_{x\rightarrow 3}\frac{\ln(\ln(x-2))}{\frac{1}{x-3}}

Now what you want to do is use l'Hôpital's rule to find that last limit.

thanks for your answer.
anyway, may i know why (ln2(x - 2))(x-3) can become (ln(x - 2))2(x-3)?

because (ln2(x - 2)) = {ln(x-2) . ln(x-2)} and it's not same with {ln(x-2)}2 right?@others any other idea please show me...
 
ln2x = (ln x)2, so as an example,

(ln2x)a = ((ln x)2)a = (ln x)2·a = (ln x)2a

just using properties of exponents.
 
For any function f, f^2(x) is defined as (f(x))^2 so, yes, they are the same thing.
 

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