Natural log (ln x) derivative question

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Homework Help Overview

The discussion revolves around finding the derivative of the function y = ln(ln(ln(x))). Participants are exploring the correct interpretation of the function and the appropriate notation for derivatives.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are questioning the notation used for the function, specifically whether it should be expressed as f(x) or f(y). There is also a discussion about the distinction between partial derivatives and ordinary derivatives, with some participants suggesting that the original poster may have misused the notation ∂y/∂x.

Discussion Status

The conversation is ongoing, with some participants providing clarifications regarding the function's notation and the derivative's notation. There is a recognition that the original poster's approach may not be correct due to the composite nature of the function, prompting further exploration of the chain rule.

Contextual Notes

There is a mention of potential confusion regarding the use of partial derivatives versus ordinary derivatives, indicating a need for clarity in the problem setup. Additionally, participants are encouraged to use parentheses for clarity in the function's expression.

SteveM19
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Homework Statement



This is to help out a 40something calc student -- thank you all in advance for your help


Homework Equations



If f (y) = ln ln ln x, what is ∂y/∂x?

The Attempt at a Solution



I came up with 1/x, which I got by applying ∂y/∂x ln x = 1/x three times, is this right? Thank you again for your help.
 
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Is that a ##f(y)##? Or like ##f(x) = y =~ ...##
 
BloodyFrozen said:
Is that a ##f(y)##? Or like ##f(x) = y =~ ...##

I might have used the terminology incorrectly --

y = ln ln ln x

What is y prime?
 
SteveM19 said:

Homework Statement



This is to help out a 40something calc student -- thank you all in advance for your help

Homework Equations



If f (y) = ln ln ln x, what is ∂y/∂x?
As BloodyFrozen already noted, that should be f(x) = ...

Also, the problem should be asking for dy/dx, not ∂y/∂x, which is the partial derivative of y with respect to x. Unless I'm missing something, you want the ordinary derivative, dy/dx.
SteveM19 said:

The Attempt at a Solution



I came up with 1/x, which I got by applying ∂y/∂x ln x = 1/x three times, is this right? Thank you again for your help.
No, it's not right. You have a composite function, y = ln(ln(ln(x))), so you need to use the chain rule a couple of times. It also might be helpful to include parentheses as I did.In response to your other question, you can take y' to be a synonym of dy/dx.
 

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