The formula d = t 2 + 2 t expresses a car's distance (in feet) from a stop sign, d , in terms of the number of seconds t since it started moving. Determine the car's average speed over each of the following intervals of time.
a. t=2 to t=5 seconds
b. t=5 to t=5.5 seconds
c. t=5.5 to t=6 seconds
?
