The issue seems to be due to restricting the function on an interval, even though the solution is within the given range. It seems to be a bug in Geogebra, and I have submitted a ticket for the developers.
Leaving this question un-deleted as documentation.
I have a function $f(x)$ defined by the
FitExp command, restricted by $0 \leq x \leq 50$.
I want to solve $f(x) = 100$, and I've tried both the
NSolve commands, but they both yield $?$ as the answer. See image below.
Is there another command I should be using for this, or is there some other input needed before this will give the answer?
All commands in CAS were entered after all the commands in the Algebra view. Meaning, $f(x)$ was defined before I tried to use