General steps for optimization?
Build the objective, fix the domain, find stationary points, compare with endpoints, answer the question.
Does a closed-interval extremum always exist?
Yes, by the extreme value theorem for continuous functions.
Max/min vs extrema?
Extrema are local; max/min are global and occur at extrema or endpoints.
Why is the result approximate?
We scan a grid; accuracy depends on density. Solve precisely when needed.
Does an open interval always have extrema?
Not necessarily; it may lack a max or min.