Help me with that

7. [0/1.42 Points] DETAILS PREVIOUS ANSWERS SCALC9 2.1.014. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The displacement (in feet) of a particle moving in a straight line is given by s = -t2 - 9t + 16, where t is measured in seconds. (a) Find the average velocity (in ft/s) over each time interval. (1) [4, 8] X ft/s (i1) [6, 8] ft /s (ii1) [8, 10] ft/s (iv) [8, 12] ft/s (b) Find the instantaneous velocity (in ft/s) when t = 8. ft/s instantaneous velocity in part (b). (c) Draw the graph of s as a function of t and draw the secant lines whose slopes are the average velocities in part (a). Then select the graph of s with the tangent line whose slope is the 10 10 10 15 10 -10 -10 -20 -15 -30 -20 10 10- 10 15 -5 10 -10 -10 -15 -20 - 20 O DO-30