4. The path of a baseball relative to the ground can be modelled by the function d(t)= ? t 2 + 8t+ 1, where d(t) represents the height of the ball in metres, and t represents time in seconds.

a. Find the average rate of change of the ball between 1 and 3 seconds.

b. Using the secant method find the instantaneous rate of change at 2 seconds.

4. The path of a baseball relative to the ground can be modelled by the function d() = - 1 + 81 + 1, where d() represents the height of the ball in metres, and represents time in seconds. a. Find the average rate of change of the ball between 1 and 3 seconds. (4 marks) b. Using the secant method, find the instantaneous rate of change at 2 seconds. (8 marks)