F (x) = - 1/3x find the average rate of change of f from - 2 to 2

Average rate = (change in y) / (change in x)

if f (x) = - x/3

r = (f (2) - f (-2)) / (2--2)

r = (-2/3-2/3) / (2+2)

r = (-4/3) / 4

r=-4/12

r=-1/3

For a line, this is always true, since all lines have a constant velocity, the average velocity over any interval is equal to the slope.