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!!
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The complete question is in the attached file. So we have to choose between two graphs. On of them is a linear model while the other is an exponential model. From the statements, we have a relationship between time and the number of teams registered. So we can establishes variables in the following form:

We also know that each week 6 teams register to participate, so:

As you can see, as x increases one week, y increases at a constant ratio of 6. Therefore, this can be modeled by a linear function given by the form:

In conclusion, <em>the linear model (first graph below) is the one that bests represents the relationship between time and the number of teams registered.</em>
The sunset is 25. how this helps!