The manager of a hardware store sells batteries for $5 a package. She wants to see how much money she will earn if she increases the price
in 10¢ increments. A model of the price change is the revenue
function R(x) = – x2 + 10x + 3000, where x is the number of
10¢ increments and R(x) is in dollars. Explain how to determine the
maximum revenue.