NUMBER 16 HELP PLZ 8TH GRADE

4+6x-3x^3 in standard form with explanations because i don’t understand

Write two subtraction equations that are equivalent to 5 + 12 = 17.

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