Question 816797
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
A retail store can sell 20 hard disk drives per week at a price of $400 each. The manager estimates that for each $10 reduction in price, 
she can sell two more drives each week. 
 a. Express the revenue function in terms of selling price. R=(20+2x)($400-10x)
 b. What price will maximize revenue? x = 15   $400 - 150 = $250
   R=(20+2x)($400-10x) = - 20x^2 + 600x + 8000 = -20(x-15)^2 + 4500 + 8000  
                                               = -20(x-15)^2 + $12,500
{{{drawing(300,300,  -50,50,-500,15000, 
 grid(1),
circle(15, 12500,0.4),
circle(0, -46/7,0.4),
graph( 300, 300, -50,50,-500,15000,0 ,-20(x-15)^2 + 12500
))}}}