DOES ANYONE KNOW HOW TO DO THIS? ONLY ANSWER IF YOU ARE FAMILIAR WITH THIS, NO TROLLS OR HACKERS RESPOND. I NEED HELP PLEASE! Help with geometry please only if you understand this. Thankyou!

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 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)