Answer:
a)[tex]R(x)=-520x^2+2600x[/tex]
b)[tex]P(x)=-520x^2+2600x-30[/tex]
c)x=2.5
d)P(x)=3220
Step-by-step explanation:
Let Demand function be D=Ax+B
We are given that When you charged $4 the demand was 520 log-ons per month
So, D = 520 , x = 4
So, 520=4A+B ----1
We are also given that When you lowered the price to $3.50, the demand increased to 780 log-ons per month.
So, D=780 , x = 3.50
So, 780=3.5A+B ----2
Substract 2 form 1
4A+B-3.5A-B=520-780
0.5A=-260
[tex]A=\frac{-260}{0.5}[/tex]
A=-520
Substitute value of A in 2
780=3.5(-520)+B
780-3.5(-520)=B
2600=B
So, D=-520x+2600
Revenue = Demand (x)=(-520x+2600)(x)
a) [tex]R(x)=-520x^2+2600x[/tex]
b) Profit = Revenue - cost
[tex]P(x)=-520x^2+2600x-30[/tex]
c)to obtain the largest possible monthly profit.
Equate the first derivative of profit to 0
P'(x)=-1040x+2600=0
[tex]x=\frac{2600}{1040}[/tex]
x=2.5
d)Now to find the largest possible monthly profit
Substitute x = 2.5 in Profit function
[tex]P(x)=-520(2.5)^2+2600(2.5)-30[/tex]
P(x)=3220