SOLUTION: Solve the problem. The cost in millions of dollars for a company to manufacture x thousand automobiles is given by the function C(x) = 5x^2 - 50x + 225. Find the number of autom

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Question 765271: Solve the problem.
The cost in millions of dollars for a company to manufacture x thousand automobiles is given by the function C(x) = 5x^2 - 50x + 225. Find the number of automobiles that must be produced to minimize the cost.

Found 2 solutions by stanbon, MathLover1:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the problem.
The cost in millions of dollars for a company to manufacture x thousand automobiles is given by the function C(x) = 5x^2 - 50x + 225. Find the number of automobiles that must be produced to minimize the cost.
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Minimum occurs when x = -b/(2a) = 50/(2*5) = 5
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Cheers,
Stan H.

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
The minimum is the C%28x%29 value that is the lowest point on a graph which is a parabola that opens up, so minimum occurs at the vertex (h,k) where

h=-b%2F2a
given:
C%28x%29+=+5x%5E2+-+50x+%2B+225
so, a=5 and b=-50
meaning that h=-%28-50%29%2F%282%285%29%29=50%2F10=5
In other words, if 5 thousand autos are produced, then the cost will be at a minimum.
Simply plug this value into the function to get:
C%285%29+=+5%2A5%5E2+-+50%2A5+%2B+225
C%285%29+=+125+-+250+%2B+225
C%285%29=100
So the minimum cost is 100 million dollars when 5 thousand autos are manufactured).

So the vertex is the point (5,100). What this means is that if we graph C%28x%29+=+5x%5E2+-+50x+%2B+225, the lowest point on the graph is (5,100).
+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+210%2C+5x%5E2+-+50x+%2B+225%29+