I NEED THIS DONE NOW PLEASE HELP ME ILL MARK YOU THE BRAINLIEST !!! Draw where the dots go on the image

Answer this question! 30 points and brainliest! only if you know the answer.

What is the missing step in this proof ?

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)