Respuesta :

legit way is vertex form

easy way is this
x value of vertex in form
f(x)=ax^2+bx+c is -b/2a
the y value is f(x value of vertex)

so

p(x)=-0.5x^2+40x-300
x value of vertex is -40/(2*-0.5)=-40/-1=40


max profit selling 40 per week
profit would be 500

Answer:

The company have to sell 40 items each week to maximize its profit.

Step-by-step explanation:

The given profit function is

[tex]p(x)=-0.5x^2+40x-300[/tex]             .... (1)

where, p is weekly profit in dollars and x is number of sold items.

In the given function leading coefficient is negative, it means it is a downward parabola and vertex of a down word parabola is point of maxima.

If a parabola is defined as

[tex]f(x)=ax^2+bx+c[/tex]                .... (2)

then the function is maximum at [tex]x=-\frac{b}{2a}[/tex].

From (1) and (2) we get

[tex]a=-0.5, b=40, c=300[/tex]

[tex]x=-\frac{b}{2a}=-\frac{40}{2(-0.5)}=40[/tex]

The given function is maximum at x=40.

Therefore the company have to sell 40 items each week to maximize its profit.