I apologize in advance for the formatting. I don't know how to put in all the symbols and what not so I am using only what is on my keyboard. I am trying to work out this equation and I'm stumped. Also I haven't taken a diff. eq. class yet, but plan to real soon. I'm working with the following: df=int(f/r^2,dr,r1,r2). I am trying to figure out the change in f between r1 and r2, but the trouble I'm having is that df is proportional to f and I just don't know how to evaluate it. Any help would be greatly appreciated. Thanks.