1 Attachment(s)

Two substitution integral evaluation questions

I've attached a picture, there's a few types of problems I'm having trouble with. I can easily solve simple integral problems involving substitution but these two are stumping me. For the first one I don't even know the deriv. of arc tan or know of a derivative that will be part of something else in the problem.

As for the second one I don't even know what to make u or du because again no part of the problem is the other part's derivative.