Answer:
If a y-value can equal two different x-values
Step-by-step explanation:
One of the easiest ways to test if something is a function or not is to graph it. If on the graph, there are multiple points on the same vertical line, or there are two points where the y-value equals different things, it will not be a function. This is called the vertical line test.
Another way to test if something is a function is to make a table with the x and y - values it has.
Not a function: Is a function:
x | 1 | 2 x | 1 | 2
y | 2| 2 y | 2| 3
This is not a function because This is a function because each
one y-value can equal two x-values. y-value has a distinct x-value.
