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## Homework Statement

Find the indefinate integral of e^2x/(1+e^x) using integration by substitution, and find the indefinate integral of x^3/sqrt(1-x^2) using integration by parts

## Homework Equations

Integration by substitution, integration by parts

## The Attempt at a Solution

The problems i'm having on these questions is choosing what to use for variables. In the first question, I decided to use u=1+e^x, but am not sure what to do about the e^2x. I know I will have to square something but am not sure what. For question 2, I have no idea what to use. I have tried making u=x^2, dv=dx and several other options but none of them seem to work. If anyone can guide me along to making the correct variable choices for these questions it would be greatly appreciated, thanks in advance.