SOLUTION: The cost C (in dollars) for a company to produce and sell x thousand gadgets is given by {{{C=1/30 x^2-2x+2530}}} What is the minimum cost? I've found that the start up cost is 2

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: The cost C (in dollars) for a company to produce and sell x thousand gadgets is given by {{{C=1/30 x^2-2x+2530}}} What is the minimum cost? I've found that the start up cost is 2      Log On


   



Question 1139591: The cost C (in dollars) for a company to produce and sell x thousand gadgets is given by C=1%2F30+x%5E2-2x%2B2530
What is the minimum cost?
I've found that the start up cost is 2530 dollars.

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

I think you meant to say C=%281%2F30%29x%5E2-2x%2B2530 instead of C=1%2F30+x%5E2-2x%2B2530
The difference is that the x%5E2 term is not in the denominator.
To make sure you do not divide by x%5E2, you would write it like this
C = (1/30)x^2 - 2x + 2530


If my assumption is correct, then we have an equation in the form
y+=+ax%5E2+%2B+bx+%2B+c
where
a = 1/30
b = -2
c = 2530

Use the 'a' and 'b' values to compute the value of h, which is the x coordinate of the vertex
h = -b/(2a)
h = -(-2)/(2*(1/30))
h = 2/(2/30)
h = (2/1) / (2/30)
h = (2/1) * (30/2)
h = (2*30)/(1*2)
h = 60/2
h = 30
The x coordinate of the vertex is 30.


The y coordinate of the vertex is k, which is defined as k = f(h)
For this problem, k = f(30)
In other words, we plug in x = 30 to find the y coordinate of the vertex.
f%28x%29+=+%281%2F30%29x%5E2-2x%2B2530

f%2830%29+=+%281%2F30%29%2830%29%5E2-2%2830%29%2B2530 Replace every x with 30; use PEMDAS to simplify

f%2830%29+=+%281%2F30%29%28900%29-2%2830%29%2B2530

f%2830%29+=+30-60%2B2530

f%2830%29+=+2500

We see that k = 2500, meaning the y coordinate of the vertex is 2500.

The vertex is at (h,k) = (30, 2500) which in this case is the lowest point of the parabola. The parabola has a lowest point any time a+%3E+0 (in this case, a = 1/30 = 0.033 approximately)

The graph confirms the answer

The graph was created with GeoGebra (free graphing software). I used the "min" feature in GeoGebra to find/display point A as shown in the diagram above.

The vertex point (30, 2500) means that if you produce and sell 30 thousand gadgets, then the minimum cost is $2500

side note: keep in mind that x is in thousands. So x = 30 really means 30,000.

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Answer:
The minimum cost is 2500 dollars