Chain rule in Calc = Chain in Log?

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Discussion Overview

The discussion centers around the relationship between logarithmic properties and the chain rule in calculus. Participants explore whether these concepts are analogous and seek clarification on the chain rule and its application in differentiation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests a similarity between logarithmic identities and the chain rule in calculus, questioning if they are the same.
  • Another participant argues that they are not related, explaining the chain rule in terms of derivatives of composite functions and providing a specific example.
  • A participant shares a link to a resource on the chain rule, indicating a desire for further exploration of the topic.
  • A question is posed regarding the derivative of the function n^x, noting that the power rule may not apply since x is not a real number.
  • A subsequent response provides a derivation for the function f(x) = n^x using logarithmic differentiation, emphasizing the use of natural logarithms in this context.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between logarithmic properties and the chain rule, with no consensus reached on their connection. The discussion includes both agreement on the mechanics of differentiation and disagreement on the analogy proposed.

Contextual Notes

Some assumptions about the nature of x and the applicability of the power rule are not fully resolved, and the discussion relies on specific definitions of logarithmic functions.

Who May Find This Useful

Individuals interested in calculus, particularly those seeking to understand the chain rule and its relationship to logarithmic functions, may find this discussion relevant.

PrudensOptimus
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I know in Logarithms loga b * logc d = loga d * logc b

and

loga b * logb c = loga c.

Chain Rule.

Now I read Calculus, I found out about the Chain rule, are they the same?? Looks like it. But because of my poor English reading, I couldn't understand the text. Can some one explain what Chain rule is?
 
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They are not related. if you have several functions as arguments to other functions like f( g( h(x) ) ), then the derivative of this is f'( g( h( x ) ) ) * g'( h( x ) ) * h'( x ) do you see the pattern? So for f(x) = 1/x and g(x) = ln(x) and h(x) = x2, f( g( h (x ) ) ) = 1/ln(x2) and the derivative would be -1/(ln(x2)2) * 1/(x2)*2x
 
http://archives.math.utk.edu/visual.calculus/2/chain_rule.2/

chain rule
Dx :wink:
 
So what is the derivative of n^x, suppose n is a real number, and x is an unknown. And power rule does not apply to this situation because x is not a real number.
 
let f(x) = nx
ln f(x) = x ln n (take ln on both sides)
f '(x)/f(x) = ln n (take the first derivative on both sides)
f '(x) = f(x)*ln n = nxln n

PS
1) ln is natural log (base e), only natural log can be used in differentiation.

2) d/dx ln f(x) = f '(x)/f(x)
 

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