The quadratic formula! We might have forgotten most of our high school lessons, but that beast is forever etched in our brain (shout out to our algebra teacher, may his mustache forever stay parallel to the floor!):

__-b ± √bČ - 4ac__

2a
So who invented the quadratic formula? Turns out that it was known for centuries, back to the days of Pythagoras and Euclid. But we had no idea is that there is a second version of the formula, derived by American mathematician David E. Muller (son of previously-profiled Nobel laurate Hermann Muller):

__2c__

-b ± √bČ - 4ac
Yes, it's quite similar to the original, but it also works. By itself, the alternate formula is not that remarkable, but Muller showed that it can be extended to solve polynomial equations of higher complexity... File that under high school lessons that we thankfully forgot.