SOLUTION: A store owner estimates that by charging "x" dollars each for a certain lamp, he can sell "10-x" lamps each week. What price will yield maximum revenue?
The revenue is R(x) = x*(10-x).
It is a parabola opened downward, with x-intercepts at 0 and 10.
The maximum is achieved at x= 5, exactly half way between x-intercepts.
So, the price of $5 per lamp will provide maximum revenue. ANSWER