Respuesta :
Answer:
[tex]y=-2\,(x-6)^2+246[/tex]
with the video game cost of x = $6
This agrees with the last option in the list of possible answers
Step-by-step explanation:
Recall that the maximum of a parabola resides at its vertex. So let's find the x and y position of that vertex, by using first the fact that the x value of the vertex of a parabola of general form:
[tex]y=ax^2+bx+c[/tex]
is given by:
[tex]x_{vertex}=\frac{-b}{2\,a}[/tex]
In our case, the quadratic expression that generates the parabola is:
[tex]y=-2x^2+24x+174[/tex]
then the x-position of its vertex is:
[tex]x_{vertex}=\frac{-b}{2\,a}\\x_{vertex}=\frac{-24}{2\,(-2)}\\x_{vertex}=\frac{-24}{-4)}\\x_{vertex}=6[/tex]
This is the price of the video game that produces the maximum profit (x = $6). Now let's find the y-position of the vertex using the actual equation for this value of x:
[tex]y=-2x^2+24x+174\\y_{vertex}=-2\,(6)^2+24\,(6)+174\\y_{vertex}=-72+144+174\\y_{vertex}=246[/tex]
This value is the highest weekly profit (y = $246).
Now, recall that we can write the equation of the parabola in what is called "vertex form" using the actual values of the vertex position [tex](x_{vertex},y_{vertex})[/tex]:
[tex]y-y_{vertex}=a\,(x-x_{vertex})^2\\y-246=-2\,(x-6)^2\\y=-2\,(x-6)^2+246[/tex]
Therefore the answer is:
[tex]y=-2\,(x-6)^2+246[/tex]
with the video game cost of x = $6