Hi. I just came back from my diffeq midterm and was surprised to see a problem with the Riemann-zeta equations on it. I think the problem went something like "Prove that [itex]\pi[/itex]/6 = 1 + (1/2)^2 + (1/3)^2 + ... " The study guide did mention that "prepare for a problem or two that may be applications or extensions of the concepts mentioned in the book". We just covered BVP, Fourier series, Wave eqn, heat eqn, and the Sturm-Liouville problems. It doesn't show up on the textbook and I've just about had it with this prof. I write down every single thing he says in class, and it's nowhere in my notes or the textbook. Is the Riemann-Zeta fair game for a diffeq midterm?