The total expenses (or costs) for the concert are given by the model:
C(x)=5x+6
Where x is the ticket price
The income (or revenue) is modeled by the function:
![I\mleft(x\mright)=-x^2+20x-30](https://img.qammunity.org/2023/formulas/mathematics/college/fut6tt6qz908h2na8vev2m8g6obzxq3rgz.png)
a) The profit is calculated as the incomes minus the costs:
P(x) = I(x) - C(x)
Substituting the above models:
![\begin{gathered} P(x)=-x^2+20x-30-(5x+6) \\ \text{Operating:} \\ P(x)=-x^2+20x-30-5x-6 \\ P(x)=-x^2+15x-36 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/nhhhcf1laqtmkzps0higl3pa8fchs8sfu7.png)
b) To calculate the break-even point, we equate the profit to zero:
![\begin{gathered} -x^2+15x-36=0 \\ \text{Multiplying by -1} \\ x^2-15x+36=0 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ffnk0cy2q9i5y0n3pyrbqqvzgz0f51bd46.png)
The polynomial can be factored:
( x - 12 ) ( x - 3 ) = 0
We have two solutions:
x=12, x=3
There are two break-even points, when the price is $3 or when the price is $12
.