Inifinity limit with natural log

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Homework Help Overview

The discussion revolves around evaluating the limit of the difference of two natural logarithmic expressions as x approaches infinity: Limx→∞ Ln(x2 - 1) - Ln(2x2 + 3).

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the manipulation of the logarithmic expressions and the application of limit properties. There is an exploration of dividing by x2 and the implications of taking the logarithm of the resulting fraction. Questions arise regarding the treatment of the logarithmic terms and the correctness of the final answer.

Discussion Status

Participants are actively engaging with each other's reasoning, with some confirming the steps taken and others questioning the final interpretation of the limit. There is a recognition of the need to apply the logarithm to the limit of the fraction derived from the original expressions.

Contextual Notes

There appears to be some confusion regarding the treatment of the logarithmic terms and the final result, with participants suggesting different interpretations of the outcome.

AlexandraMarie112
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Homework Statement


Limx--> ∞ Ln(x^2-1) -Ln(2x^2+3)

Homework Equations

The Attempt at a Solution


Ln(x^2-1)/(2x^2+3)

Then I divided the top and bottom by x^2 so in the end I got (1/2).

Is this right?
 
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AlexandraMarie112 said:

Homework Statement


Limx--> ∞ Ln(x^2-1) -Ln(2x^2+3)

Homework Equations

The Attempt at a Solution


Ln(x^2-1)/(2x^2+3)

Then I divided the top and bottom by x^2 so in the end I got (1/2).

Is this right?
What happened to the ##\ln##?
 
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Is this what you did? :

##\lim_{n\rightarrow +\infty} {\ln {(x^2 - 1)} - \ln{(2x^2+3)}}##

## = \lim_{n\rightarrow +\infty} {\ln ({\frac{x^2 - 1}{2x^2+3}})}#### = {\ln {\lim_{n\rightarrow +\infty}(\frac{1 - \frac{1}{x^2}}{2+\frac{3}{x^2}}})}##

You got the limit of the inside part as ##\frac{1}{2}## you need to take its ##\ln## to get the right answer.
 
Mastermind01 said:
Is this what you did? :

##\lim_{n\rightarrow +\infty} {\ln {(x^2 - 1)} - \ln{(2x^2+3)}}##

## = \lim_{n\rightarrow +\infty} {\ln ({\frac{x^2 - 1}{2x^2+3}})}#### = {\ln {\lim_{n\rightarrow +\infty}(\frac{1 - \frac{1}{x^2}}{2+\frac{3}{x^2}}})}##

You got the limit of the inside part as ##\frac{1}{2}## you need to take its ##\ln## to get the right answer.
Yes that's what I did. So my final answer then should be Ln(1/2) ?
 
AlexandraMarie112 said:
Yes that's what I did. So my final answer then should be Ln(1/2) ?
Right, or -ln(2)
 
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