word problem involving the maximum or minimum of a quadratic function
A supply company manufactures copy machines. The unit cost C (the cost in dollars to make each copy machine) depends on the number of machines made. If x machines are made, then the unit cost is given by the function
C(x) = 0.4x^2 - 112x + 15,045. How many machines must be made to minimize the unit cost?
Number of copy machines: ____