I'm not sure if I understand this question. By separating variables and integrating, is an obvious solution. seems to imply that , so which implies that c is not constant...? Am I missing something?

This is problem 4-a in the following assignment:

http://ocw.mit.edu/NR/rdonlyres/Math...s09_pset01.pdf

The corresponding solution set can be found:

http://ocw.mit.edu/NR/rdonlyres/Math...sol_pset01.pdf

I do not understand their solution at all.

Thanks in advance.