Implicit partial differentiation

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Homework Help Overview

The discussion revolves around finding the partial derivative \(\partial x / \partial z\) at a specific point, given an implicit function defined by the equation \(xz + y \ln x - x^2 + 4 = 0\). The context involves implicit differentiation and the relationship between the variables involved.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of implicit differentiation, particularly focusing on the correct placement of \(\partial x / \partial z\) during differentiation. There are questions about the use of the product and chain rules in the differentiation process.

Discussion Status

Some participants express uncertainty about the differentiation steps taken, particularly regarding the application of the product and chain rules. There is a recognition of potential errors in the initial attempts, and suggestions are made to clarify the differentiation process without reaching a definitive conclusion.

Contextual Notes

Participants note that \(x\) is treated as the dependent variable while \(y\) and \(z\) are independent variables, which may influence the differentiation approach. There is an acknowledgment of the complexity introduced by the logarithmic term in the equation.

morsel
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Homework Statement


Find [itex]\partial x / \partial z[/itex] at the point (1, -1, -3) if the equation [itex]xz + y \ln x - x^2 + 4 = 0[/itex] defines x as a function of the two independent variables y and z and the partial derivative exists.


Homework Equations





The Attempt at a Solution


[itex]x + y/x \partial x / \partial z - 2x \partial x / \partial z = 0[/itex]

Did I do the implicit differentiation correctly? I'm unsure about where to put [itex]\partial x / \partial z[/itex] when I differentiate.

Thanks!
 
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morsel said:

Homework Statement


Find [itex]\partial x / \partial z[/itex] at the point (1, -1, -3) if the equation [itex]xz + y \ln x - x^2 + 4 = 0[/itex] defines x as a function of the two independent variables y and z and the partial derivative exists.


Homework Equations





The Attempt at a Solution


[itex]x + y/x \partial x / \partial z - 2x \partial x / \partial z = 0[/itex]

Did I do the implicit differentiation correctly? I'm unsure about where to put [itex]\partial x / \partial z[/itex] when I differentiate.
No, this isn't correct. When you take the partial of y lnx with respect to z you have to use the product rule (and then the chain rule), and as far as I can tell, you didn't use it.

Once you have differentiated both sides of the equation, solve algebraically for [tex]\frac{\partial x}{\partial z}[/tex]
 
I think the ln term is correct. But the first term is not. Here you have to use the product and chain rule.
 
betel said:
I think the ln term is correct. But the first term is not. Here you have to use the product and chain rule.
I didn't check, but I think you're probably right. Having x be the dependent variable and y and z independent probably threw me off.
 

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