Unusual partial differentiation equation

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Homework Help Overview

The discussion revolves around calculating the partial derivatives ∂f/∂x and ∂f/∂y for the equation yf² + sin(xy) = f, where f is a function of the variables x and y. Participants are exploring the implications of f appearing on both sides of the equation and the techniques involved in partial differentiation.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster expresses confusion about how to handle the presence of f in the equation and seeks guidance on the differentiation process. Some participants suggest using the product rule and differentiating both sides with respect to x, while others question the implications of treating y as a constant during differentiation.

Discussion Status

Participants are actively engaging with the problem, with some providing initial approaches and others seeking clarification on the differentiation process. There is a mix of attempts to apply differentiation rules and questions about the setup of the problem, indicating a collaborative exploration of the topic.

Contextual Notes

There is an indication of uncertainty regarding the treatment of variables during differentiation, particularly the relationship between x and y, as well as the implications of f being a function of both variables.

rachibabes
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Homework Statement



Calculate ∂f/∂x and ∂f/∂y for the following function:

[itex]yf^2 + sin(xy) = f[/itex]

The Attempt at a Solution



I understand basic partial differentiation, but I have no idea how to approach the f incorporation on both sides of the equation nor what you would explicitly call this kind of mathematical technique. Anyone who can point me in the right direction?
 
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welcome to pf!

hi rachibabes! welcome to pf! :smile:
rachibabes said:
Calculate ∂f/∂x and ∂f/∂y for the following function:

[itex]yf^2 + sin(xy) = f[/itex]

just do ∂/∂x to the equation in the usual way (using the product rule for the yf2) …

what do you get? :smile:
 
[itex]yf^2 + sin(xy) = f[/itex]

I get:

[itex]y2f∂f/∂x +f^2∂y/∂x + cos(xy)*(x∂y/∂x+y) = ∂f/∂x[/itex]

[itex]y2f∂f/∂x +f^2∂y/∂x + x∂y/∂xcos(xy) + ycos(xy) = ∂f/∂x[/itex]

[itex]∂y/∂x[f^2 + cos(xy)] + ycos(xy) + y2f∂f/∂x = ∂f/∂x[/itex]

I have no idea how to remove the ∂f/∂x on the left hand side :/
 
hey there, rachibabes! :smile:

(just got up :zzz:)

f(x,y) is a function of the variables x and y

∂/∂x means differentiating wrt x keeping y fixed

so ∂y/∂x = … ? :smile:
 

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