An absolute maximum is a point on a curve or surface where the value of the function is greater than all other points. In other words, it is the highest point on the entire curve or surface.
This can be described formally by saying there exists an absolute maximum of the function
If a function is continuous over a closed interval, then there exists an absolute maximum within that interval. To find the absolute maximum check all the critical point within the interval and both the endpoints of the interval.
Given the function
There exists an absolute maximum over the interval