The professor wrote the differential equation f²/f'=1 on the blackboard, and asked the students to solve it.

Everybody started working with the usual methods, except for a kid at the back of the class, who happened to have skipped that material, but was very bright.

Can you solve this equation without any integration?

(In reply to Observations and maybe solution by Richard)

Sorry, no cigar. When you went from -(1/f)'=1 to -1/f=x+c, you integrated...

Posted by Federico Kereki on 2006-05-02 15:41:30