[knl]

I’m not a native speaker, so this might be a dumb question. So far, I always associated word “discover” with “something is there, someone just managed to stumble upon it while wondering around”. Thus, I find the word’s use quite strange when it comes to scientific work, especially equations —- the authors probably didn’t wonder around and invested quite a lot of work to come up with the equation.

Does it make sense to say “someone discovered an equation for X”? If not, what would be a better word?

[stormbrew]

I don't think discover implies anything about the effort put in on its own. If anything I'd say it leans towards deliberate effort, even if not always an expected result.

If it's just a fluke then more often and not I'd expect to see that spelled out as either context, or with the words you used: "stumbled upon".

At any rate, I think the reason it's used in this context in particular is because it represents that the 'equation' is not just a mathematical construct someone came up with, but that it represents observable reality in a way that is novel and perhaps unexpected. It wasn't something someone made up, it's something that usefully describes phenomena that are outside human control. Thus, they did not invent, instead they discovered.

[nightgarden]

Whether equations are invented or discovered is actually a matter of philosophy... somewhere in the areas ontology and epistemology. And the debate is not really settled, I believe.

https://www.pbs.org/wgbh/nova/article/great-math-mystery/

[Larrikin]

As a native speaker discover sounds fine to me but you are likely looking for a word like derived or calculated.