I am not getting dz[1] in this image/video snapshot

Hello @anatom

Which half of the part can you get?

Note that the chain rule actually does not work here, so if that is the part that has the problem, I am afraid the easiest way would be to remember the equation, or you have to derive it the hard way…

Here is my answer to another question on the same equation. That learner’s focus is on the ordering of the variables in the right hand side. Is that also your focus?