Limit of x^cos(1/x) as x approaches 0+ | Calculus Homework Solution

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Homework Help Overview

The discussion revolves around evaluating the limit of the expression x^cos(1/x) as x approaches 0 from the positive side, within the context of calculus.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants explore the transformation of the limit using logarithmic properties and the behavior of cos(1/x) as x approaches 0. There are attempts to apply the sandwich theorem and L'Hôpital's rule to analyze the limit.

Discussion Status

Some participants express skepticism about the correctness of the initial approach, particularly regarding the implications of cos(1/x) being negative. There is an ongoing exploration of how this affects the limit and the behavior of the expression.

Contextual Notes

Participants are considering the implications of the oscillatory nature of cos(1/x) as x approaches 0, which introduces complexity into the limit evaluation.

Snen
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Homework Statement

Homework Equations

The Attempt at a Solution


let y = lim x->0+ x^cos(1/x)
lny = cos(1/x)*lnx = (x*cos(1/x)) * (lnx/x)

x*cos(1/x) = 0 (sandwich theorem)
lnx/x = 0 (l'hopital)
so lny = 0
and y = 1
Is this correct?
 
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Snen said:

Homework Statement

Homework Equations

The Attempt at a Solution


let y = lim x->0+ x^cos(1/x)
lny = cos(1/x)*lnx = (x*cos(1/x)) * (lnx/x)

x*cos(1/x) = 0 (sandwich theorem)
lnx/x = 0 (l'hopital)
so lny = 0
and y = 1
Is this correct?
No, that doesn't look right at all.

what happens when ##\cos(1/x)## is negative?
 
PeroK said:
No, that doesn't look right at all.

what happens when ##\cos(1/x)## is negative?
PeroK said:
No, that doesn't look right at all.

what happens when ##\cos(1/x)## is negative?
Well then y would tend to infinity but the limit is x-> 0+
 
Snen said:
Well then y would tend to infinity but the limit is x-> 0+

He is not asking about what happens to x; he is asking about what happens to x^cos(1/x).
 
Ray Vickson said:
He is not asking about what happens to x; he is asking about what happens to x^cos(1/x).
tends to infinity I guess
 

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