Implicit Differentiation, and the Chain Rule

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Homework Help Overview

The discussion revolves around the application of implicit differentiation and the chain rule in calculus, specifically focusing on the differentiation of expressions involving products and compositions of functions.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the differentiation of the term xy^3 using the product rule and express confusion regarding the differentiation of y^3, questioning if it is correctly represented as 3y^2y'.
  • There is an exploration of the differentiation of trigonometric functions, particularly with the example of sin^3(sin(x^3), leading to questions about the presence of cosine factors in the derivative.

Discussion Status

Some participants have confirmed the differentiation steps, while others are seeking clarification on specific aspects of the differentiation process, particularly regarding the application of the chain rule and product rule in different contexts.

Contextual Notes

Participants are navigating through potential confusion arising from the application of differentiation rules to both polynomial and trigonometric functions, indicating a need for careful consideration of the rules in varied contexts.

QuarkCharmer
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Homework Statement


Use implicit differentiation to find dy/dx
[tex]2x^3+x^2y-xy^3 = 2[/tex]

Homework Equations


Chain Rule et al.

The Attempt at a Solution



My questions is this. When deriving something like xy^3, apply the product rule to get
[tex]1y^3 + x\frac{d}{dx}y^3[/tex]

I am confused on differentiating y^3. Is it
[tex]3y^2y'[/tex]
??

Making the solution to the mentioned equation:

[tex]y' = \frac{6x^2+2xy-y^3}{3xy^2-x^2}[/tex]
 
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QuarkCharmer said:

Homework Statement


Use implicit differentiation to find dy/dx
[tex]2x^3+x^2y-xy^3 = 2[/tex]

Homework Equations


Chain Rule et al.

The Attempt at a Solution



My questions is this. When deriving something like xy^3, apply the product rule to get
[tex]1y^3 + x\frac{d}{dx}y^3[/tex]

I am confused on differentiating y^3. Is it
[tex]3y^2y'[/tex]
??
Yes.
QuarkCharmer said:
Making the solution to the mentioned equation:

[tex]y' = \frac{6x^2+2xy-y^3}{3xy^2-x^2}[/tex]
The rest is pretty much just algebra.
 
Okay, so I am bringing down the exponent, applying the n-1, then multiplying it by the derivative of the thing in the x^n (the x). I get confused because when this happens with trigonometric equations it seems different. For instance:
[tex]sin^3(sin(x^3))[/tex]

The derivative is then:
[tex]3sin^2(sinx^3)(3x^2)[/tex] ?

I am sure there should be a cosine in there somewhere.

I want to say it SHOULD be:
[tex]3sin^2(sinx^3)cos(sinx^3)cos(x^3)3x^2[/tex]

And as always, thank you.
 
QuarkCharmer said:
Okay, so I am bringing down the exponent, applying the n-1, then multiplying it by the derivative of the thing in the x^n (the x). I get confused because when this happens with trigonometric equations it seems different. For instance:
[tex]sin^3(sin(x^3))[/tex]

The derivative is then:
[tex]3sin^2(sinx^3)(3x^2)[/tex] ?
No.
QuarkCharmer said:
I am sure there should be a cosine in there somewhere.
Yes.
You should get
[tex]3sin^2(sin(x^3))cos(x^3)(3x^2)[/tex]

That cosine factor I added is the derivative of sin(x3) with respect to x3. The 3x2 factor at the end is the derivative of x3 with respect to x.
QuarkCharmer said:
I want to say it SHOULD be:
[tex]3sin^2(sinx^3)cos(sinx^3)cos(x^3)3x^2[/tex]

And as always, thank you.
 

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