EatMeMonster

I'm trying to teach a lesson on gradient descent from a more statistical and theoretical perspective, and need a good example to show its usefulness.

What is the simplest possible algebraic function that would be impossible or rather difficult to optimize for, by setting its 1st derivative to 0, but easily doable with gradient descent? I preferably want to demonstrate this in context linear regression or some extremely simple machine learning model.

A lot of my favorite street photographers work, the photos in physical prints are only sold on Magnum. And the price feels ridiculously expensive, $10000-$20000 for a photo poster. And its not like I can get the actual digital file or negative to print myself. Is this simply the price I have to pay just for being able to hang the photo as decoration in my room?

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and its not like original art or oil painting where there will only be 1 copy ever made. the photo can be printed for very low cost. so I'm basically paying $10000, just for the "idea" of taking a photo?