Date of this Version
y = n/x seemed a very useful curve. You could use it to guide any business decision whether to rent or buy any piece of equipment.
Every such equation is not only symmetrical, it is symmetrical about the square root of the cost! That's the big bend. The business decision comes to this: would you use the equipment the square root of the dollar cost and thus get round the big bend to the shallow end of the curve?
If not, rent. If yes, buy. How very practical a square root can be.
Since then, I've seen y = n/x arise everywhere.