a math trick-3
let x be your teacher's age and a a random integer between 0 and 9 then the result is 10x - 9a = (!) = 10(x - a) + a and of course (x - a) + a = x OK? tip: try it only on openminded teachers!
Newton's Method for approximating roots of an equation (2)
Graphing Complex Numbers
Conic Section Explorations