1. The problem statement, all variables and given/known data The problem is number three (page 3) on the following link.http://panda.unm.edu/pandaweb/graduate/prelims/QM_S12.pdf I was going to type it out but it got too messy. 2. The attempt at a solution What I want to know is the relevant unitless variable substitution that the problem suggests. I tried x(r)=u(r)/r^2 thinking that u(r) is in units of r^2. This just led to a very messy diff equ. So If anyone has any other ideas on what I could use, or if this is the right substitution and i merely made a mistake.