Use the chain rule to find z(s) and z(t) if f(x,y)=x^2y+2xy^3

x(s,t)=sln(t)

y(s,t)=s^2+t^3

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- October 15th 2012, 05:42 AMallstar2Need help with a differential equation
Use the chain rule to find z(s) and z(t) if f(x,y)=x^2y+2xy^3

x(s,t)=sln(t)

y(s,t)=s^2+t^3 - October 15th 2012, 06:54 PMchiroRe: Need help with a differential equation
Hey allstar2.

Can you show us what you have tried? Do you know what the chain rule says? - October 16th 2012, 07:02 AMhollywoodRe: Need help with a differential equation
So you want to find and given:

Since z depends on both x and y,

(treating t as a constant). It's just the chain rule for two variables, except z depends on variables other than s, so you're looking for a partial derivative.

The situation for is similar.

That should get you going in the right direction. Post again if you have any more trouble.

- Hollywood