*Sometimes easy and sometimes hard, our calculus problem of the week could come from any calculus topic. If you really want to get better at calculus, following these problems is a great way to make yourself practice! Past calculus problems of the week.*

**This week’s problem:
(click “see the solution” at the bottom of post to, well, see the solution.)**

Suppose you know the following information about two functions:

Use this information to find .

is a composite function, so to find the derivative you should use the chain rule. Applying the chain rule here would give us . Therefore

Notice that if it wasn’t true that , we wouldn’t have been able to do this since we only knew .