calculus
posted by Harold .
A company manufactures and sells x cellphones per week. The weekly pricedemand and cost equations are given below P=400.5x and C(x)=20000+130x
What price should the company charge for the phones and how many phones should be produced to maximize the weekly revenue. What is maximum weekly Revenue?

revenue is sales*price
R(x) = x(400.5x) = 400x  .5x^2
dR/dx = 400  x
dR/dx = 0 when x = 400
R(400) = 400(400200) = 80000
Cost doesn't figure into revenue. Now, if you want profit, subtract cost from revenue.