Here is the second picture

The graph of the horizontal parabola is not a function.

Step-by-step explanation:

A function is a relation in which no two ordered pairs have the same input (or x-values) and different outputs (y-values).

Remember that a function can only take on one output for each input.

The Vertical Line Test allows us to know whether or not a graph is actually a function.  If a vertical line intersects the graph in all places at exactly one point, then the relation is a function.  

As you can see on the attached screenshot, each vertical line crossed the graph more than once (as evidenced by the two green dots per vertical line).  Therefore, the graph does not represent a function of x because the indicated value of x is paired with two y-values. Graphically, this means that a vertical line intersects the graph more than once.

For example, the input value, x = 9, has two corresponding output values: y = 3, and y = -3. The same thing goes with the other plotted points and vertical lines drawn.

Therefore, the graph does not represent a function.