Ink is great and completely under utilized gem in OS X, and I think you could maybe even get away with using it on the track pad without the wacom tablet if you're tight on space and don't want to seem like a total douche bringing a laptop and tablet to take note..
BUT thanks to the fact that you're using a mac, I think what might be more direct and faster even is to be able to type the darn thing? its not that hard to type your special characters:
option-b is "" for sumation, option-v is "" for square root. a few parentheses latter and you have a quick enough way to write most things, pi is option-p is "" . hold down option for a while and mash the keyboard to find what you want, or you can launch the 'special characters/unicode' typing window and figure them out that way I might use optino-5 for infinity "" and option-a for alpha "å" you can probobly do a find-replace latter to fix any oddness in what you want to see vs. what you typed.