Above is a piecewise function which means part of the graph is linear (5x) and part of the graph is a parabola (x^2 + 4)>

A closed circle means it includes the value so a closed circle would be used for the top expression of 5x and an open circle would be used for x^2 + 4.

As x=3 is included in the top equation which is a closed circle when x = 3 and y = 15 (when we substitute x = 3 into 5x)

With x >3, it is an open circle at x =3…when we substitute x = 3 into x^2 + 4 we get 13.