9514 1404 393
Answer:
120
Step-by-step explanation:
I find it pretty easy to obtain the solution by graphing ...
c(x) -13865 = 0
The positive value of x that makes this so is x = 120.
120 units will have a cost of 13,865 to manufacture.
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If you like to solve this algebraically, you can probably do it most easily by completing the square.
x^2 -5x = -65 +13865
x^2 -5x +6.25 = 13806.25 . . . . . add the square of (-5/2)
(x -2.5)² = 13806.25
x -2.5 = √13806.25 = 117.5 . . . . only the positive square root is interesting
x = 117.5 +2.5 = 120
