If answer is 'all' then give a brief explanation. If answer is 'no' then give an example and a brief explanation. If answer is 'some' then give 2 examples that illustrate the answer is not "all" or "no". Be sure to explain the 2 examples. The example must include either a specific function or a graph.

For ________ functions f, if f'(-1) = 0 then f has a local minimum or maximum at x = -1.