I’m so confused can someone help please

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)

True or false: the graph of y=f(bx) is a horizontal compression of the graph y=f(x) if b< 1

Calculate the missing value. round the answer to on decimal place. start with 70, increase it by 21%, and end up with