Dreya is saving money to purchase a $900 computer, and she saves $10 the first week. Each week after that, she saves $3 more than the previous week, except in the last week, when she reaches $900. To have a final sum of exactly $900, how much money does Dreya need to save in her final week of saving? $13
$60
$70
$73

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)