Function: contains a rule of correspondence that assigns to each element of the domain (x) and exactly one corresponding element in the range (y)
***Common Functions:
constant: y=1
identity: y=x
absolute value: y=|x|
Graph: a collection of ordered pairs (x,f(x)) such that x is a domain of f
Inverse: occurs when a functions domain and range (x and y) are reversed
***is a function if the inverse passes the horizontal line test
Composition: process of making a composite function of two functions
*** (f o g)(x)= f(g(x))
*** (g o f)(x)= g(f(x))