Is this an application of the chain rule?

Owen Ransen

Hello, please see the attached image, the author of the book says it is the application of the chain rule, but it seems different to me.

If it was a chain rule thing then there would be z-squared on the "outside" and (tk -ok) on the "inside", and z = tk-ok.

Or have I misunderstood some ways of using the chain rule?

romsek

Math Team
This is a perfect example of the chain rule.

Owen Ransen

This is a perfect example of the chain rule.
Sorry to ask, but could you go through it step by step, it does not seem to follow other examples I've found...

Owen Ransen

It may be that I did not consider the original function; does the chain rule work in this case? Can it be used in this case, because o is a function of w?

TIA!

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romsek

Math Team
It can always be used. If $o_k$ is not a function of $w_{jk}$ then $\dfrac{\partial}{\partial w_{jk}}o_k = 0$

Owen Ransen