Answer: Reflection over the y axis
A point like (2,0) that is on the red curve goes to (-2,0) on the green curve. The rule used is [tex](x,y) \to (-x,y)[/tex] which describes a reflection over the y axis. The other points use this rule as well.
In other words, every x becomes -x. Whatever the sign is for x, we swap it from positive to negative or vice versa. This means g(x) = f(-x).
