we know that The average rate of change is equivalent to the slope of the graph between the two points.
[the average rate of change]=[change in y / change in x] for x=0 y=4 for x=4 y=4 then change in y=4-4-----> 0 change in x=4-0-----> 4 [the average rate of change]=[0 / 4]------> 0