SOLUTION: an electronic store sells an average of 52 laptops per month at an average selling price that is $600 more than the cost price. for every $40 increase in the selling price, the sto

Algebra ->  Equations -> SOLUTION: an electronic store sells an average of 52 laptops per month at an average selling price that is $600 more than the cost price. for every $40 increase in the selling price, the sto      Log On


   



Question 990144: an electronic store sells an average of 52 laptops per month at an average selling price that is $600 more than the cost price. for every $40 increase in the selling price, the store sells two fewer laptops. What amount over the cost price will maximize the revenue?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
an electronic store sells an average of 52 laptops per month at an average selling price that is $600 more than the cost price.
for every $40 increase in the selling price, the store sells two fewer laptops.
What amount over the cost price will maximize the revenue?
:
let x = no. of 2 laptop decreases and also the no. of $40 increases
f(x) = (600 + 40x)(52 - 2x)
FOIL
f(x) = 31200 - 1200x + 2080x - 80x^2
f(x) = -80x^2 + 880x + 31200
Max occurs at the axis of symmetry; x = -b/(2a)
x = %28-880%29%2F%282%2A-80%29
x = 5.5
Find the amt over cost price
5.5(40) + 600 = $820 over cost at max revenue (selling 41 laptops)