Mathematicians have found 17 different ways to fill the plane with patterns that repeat in two directions. They claim that is all of them! Are these really all different? Could it be all of them? Experiment, and decide for yourself.
Chapter-38-1-1: normal vectors
Discrete Fourier Transform: GeoGebra logo
Rational Functions Anatomy
Open Middle: Basic Statistics Exercise (1)
Solving Systems of Equations by Graphing
PS3 Challenge Problem
LCM and GCD