Answer:
The cost that will result in the greatest demand is $3
Step-by-step explanation:
Let
x ------> represents the cost
y -----> represents the number of pizzas sold
we have
[tex]y=-10x^{2}+60x+180[/tex]
This is a quadratic equation (vertical parabola) open downward
The vertex is a maximum
To find out the greatest demand calculate the vertex
The equation of a vertical parabola in vertex form is equal to
[tex]y=a(x-h)^{2}+k[/tex]
where
(h,k) is the vertex
Convert the quadratic equation in vertex form
Complete the squares
[tex]y-180=-10x^{2}+60x[/tex]
Factor the leading coefficient
[tex]y-180=-10(x^{2}-6x)[/tex]
[tex]y-180-90=-10(x^{2}-6x+9)[/tex]
[tex]y-270=-10(x^{2}-6x+9)[/tex]
Rewrite as perfect square
[tex]y-270=-10(x-3)^{2}[/tex]
[tex]y=-10(x-3)^{2}+270[/tex] ----> equation in vertex form
The vertex is the point (3,270)
therefore
For the greatest demand
The cost is $3
The number of pizzas sold is 270