I don\'t have a lot of experience with Matlab. I know that you can plot equations with 2 variables like this:
ezplot(f1) hold on ezplot(f2) hold off;
"hold on" just says to not erase existing lines & markers on the current axis. you should just be able to do
ezplot(f1); hold on; ezplot(f2); ezplot(f3); hold off;
I've never used ezplot so can't help you with that one.