We are given the equation:
c = 500 + 1100 x – 100 x^2
Solve for x given the value of c = 2300
Rearrange and substitute:
- 100 x^2 + 1100 x + 500 = 2300
Divide everything by -100:
x^2 – 11 x – 5 = - 23
x^2 – 11 x = - 18
Completing the square:
(x – 11/2)^2 = - 18 + (11/2)^2
x – 11/2 = ±3.5
x = 2, 9
So x is 2 or 9
