A cup of tea costs $3 at a local cafe. Alan and his wife, Patty, have a coupon for $1 off their order. Alan says the expression 3t – 1 represents the cost for t cups of tea. Patty says the expression 3t + (–1) represents the cost. Are their expressions equivalent? Explain.

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)