1
   

Natural Log Derivatives

 
 
Reply Fri 22 Jul, 2005 01:49 pm
What is the derivative of ln((ln x^2)^5)?
  • Topic Stats
  • Top Replies
  • Link to this Topic
Type: Discussion • Score: 1 • Views: 911 • Replies: 10
No top replies

 
Brandon9000
 
  1  
Reply Fri 22 Jul, 2005 02:01 pm
Just use the chain rule.
0 Replies
 
djjd62
 
  1  
Reply Fri 22 Jul, 2005 04:28 pm
i prefer an oscillating scale of logarithmic deviations myself
0 Replies
 
foxy yellow
 
  1  
Reply Mon 25 Jul, 2005 06:16 am
oscillating scale?
Never heard of this one. What is it?
0 Replies
 
Brandon9000
 
  1  
Reply Mon 25 Jul, 2005 03:31 pm
Believe me, use the chain rule. Look it up in any calculus book.
0 Replies
 
foxy yellow
 
  1  
Reply Mon 25 Jul, 2005 07:14 pm
Chain rule
Ok, so I looked up the chain rule. It says if r(x)=(mnp)(x)=m(n(p(x)) then r'(x)=m'(n(p(x))*n'(p(x)*p'(x).

Does this translate to: ln(lnx^2)^5 = ln(ln x^2)^5 * ln x^2 = 5ln(ln x^2)*2ln x = 5/2 ln x * 2/x = 10/x lnx ? or is it 10/x + lnx?

Or is it completely out of the ballpark?

Thanks!
0 Replies
 
Brandon9000
 
  1  
Reply Mon 25 Jul, 2005 07:44 pm
Re: Chain rule
foxy_yellow wrote:
Ok, so I looked up the chain rule. It says if r(x)=(mnp)(x)=m(n(p(x)) then r'(x)=m'(n(p(x))*n'(p(x)*p'(x).

Does this translate to: ln(lnx^2)^5 = ln(ln x^2)^5 * ln x^2 = 5ln(ln x^2)*2ln x = 5/2 ln x * 2/x = 10/x lnx ? or is it 10/x + lnx?

Or is it completely out of the ballpark?

Thanks!

You stated it correctly, but then applied it incorrectly. It refers to chaining derivatives, not logarithms:

Since the derivative of ln(x) is 1/x,

ln((ln x^2)^5) = {1/[(ln x^2)^5]} * 5 ln(x^2)^4 * [1/(x^2)] * 2x

Now just simplify the terms.
0 Replies
 
raprap
 
  1  
Reply Mon 25 Jul, 2005 08:36 pm
I like to look at the chain rule as working from the inside out. IOW start with the function that is on the outside of all the parenthesis.

f(x)=ln((ln x^2)^5)=ln(g(x)) where g(x)=(ln x^2)^5
so f'(x)=1/g(x)*g'(x)

now work on the function g(x)
g(x)=h(x)^5 where h(x)=ln(x^2)
so
g'(x)=5h(x)^4*h'(x)

Now h(x)
h(x)=ln(i(x)) where i(x)=x^2
h'(x)=1/i(x)*i'(x)

Finally i(x)
i(x)=x^2
i'(x)=2x

Putting then all together
f(x)=ln((ln x^2)^5)=ln((ln(i(x))^5)=ln(h(x)^5)=ln(g(x)) and
f'(x)=[1/((ln(x^2)(^5][5(ln(x^2))^4][1/(x^2)][2x]

Now do a page of algebra and simplify, simplify. simplify.

Rap c∫;?/
0 Replies
 
foxy yellow
 
  1  
Reply Tue 26 Jul, 2005 06:40 am
Integrals
Thanks guys. I tried the problem again based on your info and got (the algebra way was too complicated for me):

5 ln(lnx^2) * 2 ln x = 5/ln x^2 *2/x = 10/ x+ lnx

or is it 10/x*lnx???

Thanks! Confused
0 Replies
 
foxy yellow
 
  1  
Reply Tue 26 Jul, 2005 03:29 pm
Maybe 10/ln(lnx)?
0 Replies
 
Brandon9000
 
  1  
Reply Tue 26 Jul, 2005 09:14 pm
foxy_yellow wrote:
Maybe 10/ln(lnx)?


ln((ln x^2)^5) = {1/[(ln x^2)^5]} * 5 ln(x^2)^4 * [1/(x^2)] * 2x

Let's cancel the first two terms:

= [5/ln(x^2)]* [1/(x^2)] * 2x

= [5/ln(x^2)]* (2/x)

= 10/xln(x^2)

= 10/2xln(x)

= 5/xln(x)
0 Replies
 
 

Related Topics

Evolution 101 - Discussion by gungasnake
Typing Equations on a PC - Discussion by Brandon9000
The Future of Artificial Intelligence - Discussion by Brandon9000
The well known Mind vs Brain. - Discussion by crayon851
Scientists Offer Proof of 'Dark Matter' - Discussion by oralloy
Blue Saturn - Discussion by oralloy
Bald Eagle-DDT Myth Still Flying High - Discussion by gungasnake
DDT: A Weapon of Mass Survival - Discussion by gungasnake
 
  1. Forums
  2. » Natural Log Derivatives
Copyright © 2025 MadLab, LLC :: Terms of Service :: Privacy Policy :: Page generated in 0.05 seconds on 06/20/2025 at 08:40:04