College Algebra word problem

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funkified

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Oct 6, 2005
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I have this word problem that I've been stuck on... if you could help i would appreciate it!


When x hundred bicycles are built, the cost per bicycle is given by the cost function C(x)=.1x^2 - .7 + 2.425, where C(x) is in hundreds of dollars.

a. How many bicycles should be built to minimize the average cost per bicycle?
b. what is the minimum cost per bicycle?


I dont even know where to start, I tried to get rid of the decimal points and factor it and use the quadratic formula but it doesnt work...

Thanks again,
Samantha
 
a) To find the minimum of a positive quadratic (such as is your "cost" function), find the vertex of the parabola. You can complete the square, or use the formula, or whatever other method they gave you for this. Since "x" is the number of hundreds of bikes, the x-coordinate of the vertex (that is, the "h" in "(h, k)") will be what they're looking for.

b) This will be the y-coordinate of the vertex (that is, the "k" in "(h, k)").

c) Please post any further algebra questions to one of the "algebra" categories. Thank you.

Eliz.
 
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