This problem is everywhere!
10:03
Most equations like this are not solvable.
10:04
Making a functional equation "work".
10:14
A practice problem from India
25:06
What is the i really doing in Schrödinger's equation?
13:38
what a great "double" functional equation!
10:10
A very interesting polynomial problem that was longlisted for the IMO!
8:31
Racine carrée d'un nombre imaginaire
41:44