Question

what is relation and function

Answer 1

Relation - if we have two sets defined under certain condition which relates them then it is called relation.
Function - any relation is said to be function if every element of set A is uniquely related to set B. where we assumed any two arbitrary sets.

Answer 2

In the first relation, when there was a sale, the first three ordered pairs all had the same input with different outputs. ... When this is the case, we call the relation a function. In mathematics, a function is a relation in which no input relates to more than one output.
A function is a special type of relation where every input has a unique output. Definition: A function is a correspondence between two sets (called the domain and the range) such that to each element of the domain, there is assigned exactly one element of the range
A function is a "well-behaved" relation. Just as with members of your own family, some members of the family of pairing relationships

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