In ABC, show that midsegment DE is parallel to AC and that DE = 1/2AC

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)

10 points? me . its important ‼️‼️

Ineed to know the ordered pairs for this equation i need the answer quick because it’s a timed test