TThe position of a moving particle is given by the position function
f(t) = −10t − t2 − 0.3t3 + 0.1t4, 0 ≤ t ≤ 8.
Estimate values from the graphs to answer the following questions.
(a) At what time does the particle reverse direction? (Round your answer to one decimal place.)
t =


(b) When is the displacement positive? (Round your answer to one decimal place. Enter your answer using interval notation.)


When is the displacement negative? (Round your answer to one decimal place. Enter your answer using interval notation.)


(c) When is the particle's acceleration positive? (Round your answer to one decimal place. Enter your answer using interval notation.)
When is the particle's acceleration negative? (Round your answer to one decimal place. Enter your answer using interval notation.)


(d) Write equations for the velocity and acceleration functions.
f'(t)=
f''(t)=