Select all the fractions that are equivalent to 4/5. Use the area models to help. An area model showing five equal parts. Four of the parts are shaded. An area model showing ten equal parts. Eight of the parts are shaded. An area model showing fifteen equal parts. Twelve of the parts are shaded.
A. 610
B. 810
C. 815
D. 1015
E. 1215

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)