Find dy/dx, which way should I use?

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Homework Help Overview

The discussion revolves around finding the derivative dy/dx for the equation Y^x = X^y, which involves logarithmic differentiation and the application of implicit differentiation techniques.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the equivalence of different forms of the equation before differentiation, with some suggesting that the order of differentiation does not matter as long as the equality is maintained. Others express concern about potential pitfalls in one of the suggested methods, questioning its validity.

Discussion Status

The conversation includes attempts to clarify terminology, such as the distinction between "differentiate" and "derive." There is an ongoing exploration of the implications of different approaches to differentiation without reaching a consensus on the best method.

Contextual Notes

Participants note that there may be concerns about the safety of certain methods as indicated by an instructor, suggesting that some approaches could lead to incorrect solutions.

Mamdoh Abughalion
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Homework Statement

.[/B]
Find dy/dx
Y^x = X^y

Homework Equations


F'( Ln(x)) = 1/x
Lnx^y = yLnx

The Attempt at a Solution


Ln(Y^x) = Ln(X^y)
X • Lny = Y • Lnx , should I differentiate now or :
Y = X • Lny/Lnx
Y = X • Logxy , then differentiate ?
 
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It does not matter when you differentiate as long as the equality you are differentiating is equivalent to the original one.
 
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Mamdoh Abughalion said:

Homework Statement

.[/B]
Find dy/dx
Y^x = X^y

Homework Equations


F'( Ln(x)) = 1/x
Lnx^y = yLnx

The Attempt at a Solution


Ln(Y^x) = Ln(X^y)
X • Lny = Y • Lnx , should I derive now or :
Y = X • Lny/Lnx
Y = X • Logxy , then derive?
To find a derivative, you differentiate. The word derive means something else.
 
Orodruin said:
It does not matter when you differentiate as long as the equality you are differentiating is equivalent to the original one.
I know that , but my instructer told me that the second way is too much " dangerous " and may lead to wrong solution .
 
Also, please don't write ##F'(\ln x) = \frac 1 x##. There is no ##F##. What you mean, and should write, is ##(\ln x)' = \frac 1 x## when you want to give a derivative formula.
 
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