A function is the relationship that pairs each input value with exactly one output value. A relation is a pairing of numbers in one set (the domain) with numbers in another set (the range).
Work Step by Step
Every function is a relation. Each input value is one number in the domain, and each output value is one number in the range. Not all relations are functions. Example: [(6,5), (4,3), (4,2)] is not a function since the input number (domain) 4 is mapped to two different numbers in the range.