About the ambiguity: If I write f^{-1}(x), without context, you have literally no way of knowing whether I am talking about a multiplicative or a functional inverse, which means that it is ambiguous. It's correct notation in both cases, used since forever, but you need to explicitly disambiguate if you want to use it.
I hope this helps you more than the stackexchange post?
If I write f^{-1}(x), without context, you have literally no way of knowing whether I am talking about a multiplicative or a functional inverse, which means that it is ambiguous
The inverse of the function is f(x)^-1. i.e. the negative exponent applies to the whole function, not just the x (since f(x) is a single term).
We've been at this point, I'm not going to explain this again. But you weren't able to read a single sentence of a wikipedia article without me handfeeding it to you, so I guess I shouldn't be surprised. I'm sorry for your students.
Apparently you can't read either textbooks or wikipedia and understand it.
Also, wait, you're just a tutor and not actually a teacher? Being wrong about some incredibly basic thing in your field is one thing, but lying about that is just disrespectful, especially since you drop that in basically every sentence.