A function that satisfies the condition for all inputs . You can tell an even function from its graph: Its graph is symmetric about the -axis.

A function that satisfies for all inputs . You can tell an odd function from its graph: Its graph is taken to itself when you reflect it across both the - and -axes. This can also be seen as a 180 rotation about the origin.

The vertex form of a quadratic expression is , where , , and are constants and . The vertex of the graph is at the point .