Answer:
-16feet/second
Step-by-step explanation:
If the height or the ball is modelled nu the equation f(t) = -16t^2 +20t +4
The average rate of change is the velocity of the ball.
Velocity = {d(f(t)}/dt = -32t+20
The velocity of the ball over the interval [0.75, 1.25] can be gotten by taken the difference of the velocity at t = 0.75 from when t = 1.25
f'(t) = -32t+20
f'(0.75) = -32(0.75)+20
f'(0.75) = -24+20
f'(0.75) = -4ft/s
At t = 1.25s
f'(1.25) = -32(1.25)+20
f'(1.25) = -40+20
f'(1.25) = -20ft/s
Rate of change = f'(1.25) - f'(0.75)
Rate of change in height = -20-(-4)
Rate of change in height = -16ft/s
