Implicit Differentiation, and the Chain Rule

QuarkCharmer
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Homework Statement


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

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
1y^3 + x\frac{d}{dx}y^3

I am confused on differentiating y^3. Is it
3y^2y'
??

Making the solution to the mentioned equation:

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

Homework Statement


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

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
1y^3 + x\frac{d}{dx}y^3

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

y' = \frac{6x^2+2xy-y^3}{3xy^2-x^2}
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:
sin^3(sin(x^3))

The derivative is then:
3sin^2(sinx^3)(3x^2) ?

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

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

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:
sin^3(sin(x^3))

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

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:
3sin^2(sinx^3)cos(sinx^3)cos(x^3)3x^2

And as always, thank you.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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