Thread: Is this wrong? (differential operator)

I believe this soln has an error.



Am I right?

Originally Posted by scorpion007

I believe this soln has an error.



Am I right?

What is ? What are and ?

Sorry, I didn't think it mattered, given the context. But here they are:



The reason I say it's wrong is because when you distribute the x through the first term, you end up with and similarly for the second term with y.

(Also, we assume the mixed derivatives are equal)

Originally Posted by scorpion007

Sorry, I didn't think it mattered, given the context. But here they are:



The reason I say it's wrong is because when you distribute the x through the first term, you end up with and similarly for the second term with y.

(Also, we assume the mixed derivatives are equal)

We needed to know that

And so you're just applying the chain rule? That is what that jpeg is of, right? Double application of the chain rule?

Isn't x = x(s, t) and y = y(s, t)?

Yes, this is the chain rule for partial derivs.