Charles buys 30 packs of pens. There are 15 pens in each pack.
Each pack costs £4.60.
Charles sells each pen for 80p but he only manages to sell
3
5
of the pens.
How much profit did he make

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)