The graph shows the two points (0,-4) and (-2,2) are on the parabola. The x coordinates of both points are from x = 0 and x = -2 as given in the instructions. Compute the slope of the line through those points. The slope of this line is the exact same as the average rate of change from x = -2 to x = 0.
m = (y2 - y1)/(x2 - x1)
m = (2 - (-4))/(-2-0)
m = (2 + 4)/(-2-0)
m = 6/(-2)
m = -3
A negative slope means the line slopes downhill as you move from left to right. This is a negative average rate of change.
