To do good maths questions, you will get much better results using an add-on like STACK. STACK comes with lots of good questions on topics like algebra and calculus. You can see them at http://stack.bham.ac.uk. Go into the demo course. With the standard Moodle question types, your options are limited, and I don't know of any question banks, but you could check out moodle.net: http://moodle.net/mod/data/view.php?id=3
Hi Tim,
Thanks for your answer. I would prefer not to have to install another module, since this would mean some more administrative tasks. But I've keep hearing about this STACK, so I guess eventually I'll fold and take it.