SOLUTION: Looking at {{{f(x)=-0.2x^2+12x+11}}} After how many days will the peak or low occur?

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Looking at {{{f(x)=-0.2x^2+12x+11}}} After how many days will the peak or low occur?       Log On


   

Question 130299: Looking at f%28x%29=-0.2x%5E2%2B12x%2B11

After how many days will the peak or low occur?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
The peak corresponds to the vertex of the parabola. So let's find the x-coordinate of the vertex


In order to do that, we can use this formula:

x=-b%2F%282a%29

From the equation y=-0.2x%5E2%2B12x%2B11. we can see that a=-0.2 and b=12

x=%28-12%29%2F%282%2A%28-0.2%29%29 Plug in b=12 and a=-0.2


x=%28-12%29%2F%28-0.4%29 Multiply 2 and -0.2 to get -0.4


x=30 Divide


So the x-coordinate of the vertex is x=30




So at the x-coordinate of the vertex, the peak will occur. So on the 30th day, the peak in ticket sales will occur.