The revenue function for a sound system is
R(x) = 300x - x2 dollars
where x denotes the number of units sold.
(a) What is the function that gives marginal revenue?
(b) What is the marginal revenue if 50 units are sold, and what does it mean?
(c) What is the marginal revenue if 200 units are sold, and what does it mean?
(d) What is the marginal revenue if 150 units are sold?
(e) As the number of units sold passes through 150, what happens to revenue?