Answer:
290
Explanation:
Average acceleration is the change in velocity over change in time.
First, find the velocity by taking the derivative of position.
v(t) = dx/dt
v(t) = 38t + 21t²
At t = 3 and t = 9:
v(3) = 303
v(9) = 2043
So the average acceleration is:
a = Δv / Δt
a = (2043 − 303) / (9 − 3)
a = 290
Use appropriate units.