1. The problem statement, all variables and given/known data Quick question... I have seen both being used : f(x,a) and f(x;a). What is the usual convention? Are both acceptable to denote functions of 2 variables (in this case f is a function of both x and a). Or are there vital differences between the two that I don't know about? Thanks! :) 2. Relevant equations N.A. 3. The attempt at a solution N.A.