The cost "C" of operating a concrete-cutting machine is related to the number of minutes "n" the machine is run by the function: C(n)=2.2n⋀2-66n+655. For what number of minutes is the cost of running the machine a minimum? What is the minimum cost?

Answer 1

dC/dn = 4.4n - 66 = 0 for a min of C
4.4n = 66
n = 66/4.4 = 15

cost(15) = ..... put 15 back into original equation