SamizdatMath

Are you teaching the quadratic formula to your students? Are you teaching it the same way you learned it in high school? Or maybe college? Or maybe on the street somewhere? Then you're probably teaching it WRONG AF. It's okay: I've been teaching the quadratic formula WRONG AF for decades. I didn't know it, but I was. It wasn't until one day I was working with a group of my college students and made a mistake that I had a realization: we've been teaching the quadratic formula WRONG AF for decades

This is an old brain teaser that someone told me, and which I shortened and clarified, as well as added clues for your students to use, as well as three different explanations for how to solve it. Basically, the problem goes like this: you have 7 people who want to find the average of their salaries. The only problem is that no one wants to tell anyone how much they earn. How will you find the average without anybody stating their actual salary? I've run this problem by all my techie type frie