Please someone answer the question I need help with this too I need problem 5 and 6

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)

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x

Rewrite so the subject can be y in the formula d=m-y/y+n