Remembering this equation, and helping others to remember this equation, has bedeviled students of mathematics for centuries. Now, thanks to the magnificent fight song The Victors, there is an easy solution to this problem. Here is the Quadratic Song (sung to the tune of The Victors). Fist pumps are optional.
Neg!-a-tive b plus or minus
Square! root of b-squared minus
4! a! c all over
2 times a (repeat)
Your kids will thank you for teaching them this song.