Natural log (ln x) derivative question

In summary, the conversation is about a student seeking help with a calculus problem involving the function f(y) = ln ln ln x and its derivative. After some clarification of the problem and terminology, it is determined that the student needs to use the chain rule to find the derivative, which is not 1/x as originally thought. The conversation also touches on the use of y' as a synonym for dy/dx.
  • #1
SteveM19
11
0

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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  • #2
Is that a ##f(y)##? Or like ##f(x) = y =~ ...##
 
  • #3
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?
 
  • #4
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.
 

What is the derivative of ln x?

The derivative of ln x is 1/x. This can be derived using the power rule for logarithmic functions.

Why is the derivative of ln x equal to 1/x?

The derivative of ln x is equal to 1/x because ln x is the inverse function of e^x, and the derivative of e^x is equal to e^x. Using the chain rule, the derivative of ln x can be expressed as 1/x * (1/x), which simplifies to 1/x.

What is the domain of ln x?

The domain of ln x is all positive real numbers, as the natural logarithm function is only defined for positive values of x. If x is negative, ln x is undefined.

What is the difference between ln x and log x?

The main difference between ln x and log x is the base of the logarithm. Ln x is the natural logarithm, with a base of e, while log x can have a base of any positive number. Another difference is that ln x is the inverse function of e^x, while log x is the inverse function of the corresponding exponential function with the specified base.

How can the derivative of ln x be used in real-world applications?

The derivative of ln x can be used to calculate rates of change in many real-world situations, such as population growth, interest rates, and chemical reactions. It can also be used in various fields of science, including physics, biology, and economics, to model and analyze natural phenomena.

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