Answer:
Monthly fee that will yield the maximum monthly revenue is $12.5
Then the value of the maximum monthly revenue is $156 250
Step-by-step explanation:
x - value of decrease
1000x - number of new subscribers for $x decrease
10000+1000x - number of subscribers after $x decrease in the monthly fee
15-1x the monthly fee after $x decrease
f(x) = (10000 + 1000x)(15 - x) ← quadratic function
For quadratic function given in standard form: f(x) =a(x-h)²+k where a<0 the f(x)=k is the maximum value of function, and occurs for x=h
[tex]h=\frac{-b}{2a}\ ,\quad k=f(h)[/tex]
Expressing given function to standard form:
f(x) = 1000(10 + x)(15 - x)
f(x) = 1000(150 - 10x + 15x - x²)
f(x) = 1000(-x² + 5x + 150)
f(x) = -1000x² + 5000x + 150000 {a=-1000<0}
[tex]h=\dfrac{-5000}{2\cdot(-1000)}=\dfrac{5000}{2000}=\dfrac52=2.5\\\\k=f(2.5)=1000(10+2.5)(15-2.5)=1000\cdot12.5\cdot12.5=156\,250[/tex]
15-2.5 = 12.5
