The "other" type of derivative word problem (related rates are the big one). The way to spot these is that they'll always ask you to "maximize" or "minimize" something: the area of a rectangle, the volume of a box, the profit of a random company... No matter what the situation, the process is always the same: write down a formula and find the maxima or minima.

OOPS! To create playlists you must logged in.

If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)