1. Find a formula for a function that has vertical asymptotes x = 7 and x = 9 and horizontal asymptote y = 7.
2. (a) A tank contains 5000 L of pure water. Brine that contains 35 g of salt per liter of water is pumped into the tank at a rate of 25 L/min. Show the concentration of salt t minutes later (in grams per liter).
(b) What happens to the concentration as t → ∞?
3. Find the limit, if it exists. (If an answer does not exist, enter DNE.)
limx → ∞(x - 7) / (x2 + 2).