Here we’ll practice on maxima and minima concepts.

If , then is a local extremum of .
If is continuous, when and when , then is a local max.
A function on a closed interval must have a local extremum.
If has a local max at , then its square must also have a local max at

If does not exist, then cannot have a local extremum at
If and both have local minima at , then their sum has a local minima at as well.
If is differentiable and decreasing on , then on
If and both have local minima at , then their product has a local minima at as well.