Answer:
The company will break even at x=1 and x=4.
Step-by-step explanation:
The given profit function is
![P(x)=-x^4-2x^3+21x^2+22x-40](https://tex.z-dn.net/?f=P%28x%29%3D-x%5E4-2x%5E3%2B21x%5E2%2B22x-40)
Where, x is number of commercials.
Use synthetic division or long division to find the factors of the function.
![P(x)=(x-1)(x^3+3x^2-18x-40)](https://tex.z-dn.net/?f=P%28x%29%3D%28x-1%29%28x%5E3%2B3x%5E2-18x-40%29)
![P(x)=(x-1)(x+2)(x^2+x-20)](https://tex.z-dn.net/?f=P%28x%29%3D%28x-1%29%28x%2B2%29%28x%5E2%2Bx-20%29)
![P(x) = -(x - 4) (x - 1) (x + 2) (x + 5)](https://tex.z-dn.net/?f=P%28x%29%20%3D%20-%28x%20-%204%29%20%28x%20-%201%29%20%28x%20%2B%202%29%20%28x%20%2B%205%29)
Equate P(x)=0, to find the break even points.
![-(x - 4) (x - 1) (x + 2) (x + 5)=0](https://tex.z-dn.net/?f=-%28x%20-%204%29%20%28x%20-%201%29%20%28x%20%2B%202%29%20%28x%20%2B%205%29%3D0)
Use zero product property and equate each factor equal to zero.
![x=4,1,-2,-5](https://tex.z-dn.net/?f=x%3D4%2C1%2C-2%2C-5)
Therefore the zeros of the function P(x) are 4, 1, -2 and -5. Since x is number of commercials, therefore the value of x must be positive. Therefore the company will break even at x=1 and x=4.
The higher degree of the function is even and the leading coefficient is negative. So,
![P(x)\rightarrow -\infty \text{ as }x\rightarrow \infty](https://tex.z-dn.net/?f=P%28x%29%5Crightarrow%20-%5Cinfty%20%5Ctext%7B%20as%20%7Dx%5Crightarrow%20%5Cinfty)
![P(x)\rightarrow -\infty \text{ as }x\rightarrow -\infty](https://tex.z-dn.net/?f=P%28x%29%5Crightarrow%20-%5Cinfty%20%5Ctext%7B%20as%20%7Dx%5Crightarrow%20-%5Cinfty)
Since the value of x must be positive, therefore the left end point is y-intercept of the graph, i.e., (0,-40).
Therefore the company faces huge loss when the number of commercials increases unboundly.
The graph of the function is given below.