Plz help me with this question

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5

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)

Heather is riding a quadratic function that represents a parabola that touches but does not cross the x-axis at x=-6