Or roots. Or solutions. Or x-intercepts. Depending on your teacher, approximation can seem like a really confusing topic. Equations of lines, derivatives, crazy drawings and diagrams. But when it comes time to actually do the problems, it's basically just time to memorize this chart that you can plug-and-chug your way through every time.
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...)