On the coordinate plane shown, each grid unit represents 10 feet. Polygon QRST has vertices Q(10, 30), R(−20, 30), S(−20, −10), and T(10, −10), and represents the floor plan of a room. Find the perimeter and area of the room

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)