Expalin what the vertical line test is and it used?

You use the vertical line test to see if a function is relation is a function

Step-by-step explanation:

A function is a relation with only one output for every input. That means that if the x value and two y values, it is not a function.

The vertical line test is a method that is used to determine whether a given relation is a function or not ... The vertical line test supports the definition of a function. That is, every x-value of a function must be paired to a single y-value.