9. Let f(x) = x3+ 12x2 -60x + 20 a) On what interval is f concave downward ? b) On what interval is f concave upward ? c) State any inflection points (give ordered pair(s)) 10. A baseball team plays in a stadium that holds 54000 spectators. With the ticket price at $8 the average attendance has been 24000. When the price dropped to $6, the average attendance rose to 27000. Assume that attendance is linearly related to ticket price. a) Find the demand function d(x) where x is the price. b) Find the elasticity function E(x) c) What ticket price would maximize revenue