G(x, y)={mod((x),2)>0,-1} im doing a puzzle and this is a equation in the puzzle, i know the equation might be incomplete but the only other numbers i have for this is -6, -6 please do not answer "this answer might be spelled incorrectly" only comment that and i might be able to help

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)