Question

I am supposed to find the ticket sales of a concert using this formula:

N(x)= -0.3x^2 + 6x + 15

X represtents the number of days since the concert was first announced. I need to find out when daily ticket sales will peak and how many tickets will be sold on that day. How do i work out this problem I don't know the first place to start! please help.

Answer 1

If you are not in Calculus, then I would graph the equation to find x for the maximum sales.

Answer 2

So I should find the vertex?

Answer 3

I assume no calculus, therefore we must look at the shape of this curve.
it is of form ax^2 + bx + c, a parabola
y = -.3 x^2 + 6 x + 15
we need to find the vertex
complete the square
y/-.3 = x^2 +6/-.3 x +15/-.3
x^2 - 20x -50 = -3.33 y
x^2 -20 x = -3.33 y +50
x^2 -20 x +100 = -3.33y +150
(x-10)^2) = -3.33 ( y - 45)
vertex at (10,45)
10 days, 45 tickets