There is a very

silly, but handy,

mnemonic for remembering this

formula. It runs as follows:

If you pretend you're Santa Claus, you could call f(x) "Hi" (as in, high, on top), and g(x) "Ho" (rhymes with "low"). Then the formula is "HoDeeHi minus HiDeeHo over HoHo".

(dy / dx) = __HoDeeHi - HiDeeHo__
(Ho)(Ho)

You will probably feel like an

idiot reciting this to

calculus students, but hey, whatever works.