This week in math I learned the difference between a relation and a function. A relation is when one input has several outputs. Like one person would have many friends. Whereas a function is when an input has only one output, like a couple. A hint is that on a graph, almost all straight lines are functions, except for vertical lines. Vertical lines are relations. You can also tell if something is a relation on a graph if you can draw a straight vertical line in between a curve or line.

Examples: