Finding dy/dt using the chain rule and a given equation

[kweig]

Homework Statement

So I'm trying to find dy/dt. I used the chain rule to find dx/dt. I just don't understand how to put that answer back into an equation to find dy/dt

Homework Equations

4x^3-6xy^2+3y^2=228

The Attempt at a Solution

I found dx/dt=3 x=-3 and y=4
So how/what equation do I use to find dy/dt

 

[Dick]

Homework Statement

So I'm trying to find dy/dt. I used the chain rule to find dx/dt. I just don't understand how to put that answer back into an equation to find dy/dt

Homework Equations

4x^3-6xy^2+3y^2=228

The Attempt at a Solution

I found dx/dt=3 x=-3 and y=4
So how/what equation do I use to find dy/dt

Differentiate 4x^3-6xy^2+3y^2=228 with respect to t, put your values for x, y and dx/dt into that and solve for dy/dt.

 

[kweig]

The implicit differentiation?

 

[Dick]

The implicit differentiation?

Of course.

 

[kweig]

I got dy/dt=(2x^2-y^2)/(y(2x-1))

 

[Dick]

I got dy/dt=(2x^2-y^2)/(y(2x-1))

An expression for dy/dt ought to have some dx/dt's in it. I think what you've got there is dy/dx. Can you think how to use that to get dy/dt?

 

[kweig]

Yep! I figured it out. Thank you!