mathematics for management

7. (10) The demand function for a certain brand CD is given by p=0.01x0.2x+8 where p is the unit price in dollar and x is the quantity demanded each week, measured in units of thousand. Determine the consumers' surplus if the market price is set at $5/disc. 8. (10) Let f(x, y, z) = xyz + xyz + 3xy - 4z. Compute f(1,1,0), fy(1,1,0), and f (1,1,0), and interpret your results. 9. (10) Sejong Travel Agency's monthly revenue depends on the amount of money x (in thousands of dollars) spent on advertising per month and the number of agents y in its employ in association with the rule R(x, y) = x-0.5y2 + xy + 8x + 3y + 20 Determine the amount of money the agency should spend per month and the number of agents it should employ to maximize its monthly revenue