The manager of a bookstore determined that when a certain new novel is priced at p dollars per copy, the daily demand q = f(p) = q(p) will be given by the equation: 2p^2 +5q^2 =900, 1≤p≤21. (a) Determine for which prices the demand is elastic, inelastic, or of unit elasticity. (b) What prices will cause revenue to increase or decrease? What price will result in maximum revenue? (c) Suppose the price is $10. What is the approximate change in demand if the price lowered by 3.5%?