The question is-
Aki’s Bicycle Designs has determined that when x hundred bicycles are built, the average cost per bicycle is given by C(x) = 0.6x^2-0.8x+10.618, where C(x) is in hundreds of dollars. How many bicycles should the shop build to minimize the average cost per bicycle?
I think- the function, C(x), gives the average cost when x hundred bicycles are made. This is my quadratic function right? Where the coefficient of x^2 is positive? Then the minimum value will be at the vertex?
So I need the form y=a(x-h)^2+k to get my minimum value- x=h.
Now, I need to separate the constant part from the remainder of the function and factor the coefficient of x^2 from the terms containing x. (I am supposed to round to three decimal places if needed.
C(x) = 0.6x^2-0.8+10.618
Now I am lost
C(x)= 0.6 (x^2-?.??x)+10.618
Where does this equation come from?
With that I can complete the square by taking half the answer and squaring it.
8 answers
C(x) = 0.6x^2-0.8x+10.618
= 0.6(x^2 - 1.333x + 17.697)
= 0.6 (x^2 - 1.333x +0.444 + 17.253)
= 0.6 [(x- 0.667)^2 + 17.53]
There is a minimum average cost when x = 0.667 hundred bikes (or 67 bikes).
These must be pretty expensive bikes. The minimum cost is 10.35 hundred dollars ($1035)
y = x - 5 so the equation becomes:
x*(x - 5) = 24
expand: x^2 - 5x - 24 - 0
Factor by sum and product method:
(x - 8)(x + 3) = 0 so x = 8 or x = -3
since the integers are positive, the solution is x = 8, and y = x - 5, so
y = 8 - 5, y = 3
the two integers are 3 and 8
5654353574768
756746