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Derivative of ln(ln x)

by Physicsnut
Tags: derivative, lnln
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Physicsnut
#1
Mar5-12, 07:48 AM
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1. The problem statement, all variables and given/known data

Differentiate $$ln(lnx)$$

2. Relevant equations



3. The attempt at a solution
My solution:
Let $f(x)=lnx$, since${d/dx}ln f(x)={f'(x)/f(x)}$,
${d/dx}ln(lnx)={{1/x}/lnx}/times {1/x}
={1/x^2lnx}$.
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tiny-tim
#2
Mar5-12, 07:53 AM
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Hi Physicsnut! Welcome to PF!
Quote Quote by Physicsnut View Post
Let f(x)=lnx, since d/dx ln f(x) = {f'(x)/f(x)},
yes
{d/dx}ln(lnx) = {{1/x}/lnx}/times {1/x}
nooo
Fredrik
#3
Mar5-12, 09:45 AM
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Surround your LaTeX code with either ## or $$. A single $ doesn't work. This is deliberate, because it would have confused people who don't use LaTeX but write stuff about money. LaTeX guide for the forum.

HallsofIvy
#4
Mar5-12, 12:31 PM
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Derivative of ln(ln x)

##e^x##
$$x^n$$
[itex]\int f(x)dx[/itex]
[tex]\frac{df}{dx}[/tex]

Wow! All this time I have been using "itex" and "tex"!
Fredrik
#5
Mar5-12, 02:19 PM
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Quote Quote by HallsofIvy View Post
Wow! All this time I have been using "itex" and "tex"!
The simplified tags have only been available since December 20.


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