Explanation:
A function is a relationship where any one x-value/input only has <u>one </u>corresponding y-value/output. (note: a y-value can have multiple x-values).
> This can be called "assigning one y-value to every x element".
The vertical line test places a line that would connect all y-values of an x-value (that is, if it were to have multiple y-values). If multiple points can be found along the vertical line, it is, therefore, by the definition of a function, not a function. (Because an x-value will have more than one y-value).
So, a graph that fails the vertical-line test does not represent a function because an x-value will correspond with more than one y-value.
hope this helps!!
