A reader sent in this question: “ Hi. I was wondering if you could help me figure out finding a complex root problem. If you could explain how it's done that would be great The simple, easy solution ...

In this paper we shall prove the following theorem: Let K be a differential field of characteristic zero. Let φ and ψ be elements of a differential field extension of K such that (i) φ ≠ 0 and ψ ≠ 0; ...