Change of Variable...the Dirty Integral

As we attempt to undo chain rule-esque intergrals remember the following:

1. Pick a good "u".  It's is usually the "inside stuff"...but doesn't have to be. 
2. Find "du/dx"...take the derivative of u.
3. Your "dx" and anything else left over in the intergral should show up once you find "du/dx".  Sub that into your intergral.  You've now successfully changed your variables from "x" to "u".  Hopefully, the new intergral is simplier.  Take the integral.
4. Resub to get "x" in your answer.

Easy as pi... :)