Find the absolute maximum and minimum of quadratic function on given interval

In this example problem, we find the absolute maximum (abs max) and absolute minimum (abs min) of a quadratic function (second 2nd degree polynomial) by taking its first 1st derivative and determining a critical value (critical number) by setting it equal to zero and solving for our variable. We then determine that the critical value will be a maximum of the function by using the second 2nd derivative test. Finally, we evaluate our critical number and the endpoints of the given interval in the original function. We compare the results to determine the absolute max and absolute min of the function and the values at which they occur.

[mitra.]

is absolute maximum and strict global maximum same? can you please share some material to refer for strict global maxima