For a function f(x), the absolute maximum and the absolute minimum can be calculated in an interval [a,b] by following the process listed below.
- Step 1: determine all the critical numbers of f within the given interval [a, b].
- Step 2: mark each critical number from step 1 into the function f(x).
- Step 3: mark the endpoints (a and b) into the function f(x).
The largest value can be regarded as the absolute maximum whereas the smallest value can be regarded as the absolute minimum.