Hi!
Here is my function:

My task is to find:

I think I know how to find ∂u/∂x, but I have no idea how to find ∂/∂z(∂u/∂x). Here is how I found ∂u/∂x:

Does someone know how to find ∂/∂z(∂u/∂x)?
I appreciate any help

 

∂u/∂x is simply the derivative of u with all variables except x help constant. Once you get this result, find the partial derivative of the result, this time holding all variables except z constant. That is ∂/∂z(∂u/∂x).

e.g. If you had u = xzy then ∂/∂z(∂u/∂x) = ∂/∂z(zy) = y