When the math becomes more advanced, it seems reasonable to upload an auxilary file. For example, some of the questions in my recent algebra quiz are dealing with the plots. To answer those questions, the students are asked to open pdf files generated from any advanced math editor (mathematica in my case) and answer multiple choice questions looking in that file....
well, I tried to upload the file, but it exceeded the allowed size.
You can send your email address to firstname.lastname@example.org, and I will send the file directly. Naturally, such a file can also contain some advanced math formulas.