SOLUTION: Solve. Use a graphing calculator if necessary. See Examples 9-11. (Objective 8) The cost C in dollars of operating a certain concrete-cutting machine is related to the number of

Question 1169985: Solve. Use a graphing calculator if necessary. See Examples 9-11. (Objective 8)
The cost C in dollars of operating a certain concrete-cutting machine is related to the number of minutes n the machine is run by the function
C(n) = 1.2n2 − 24n + 690.
For what number of minutes is the cost of running the machine a minimum? What is the minimum cost?
Question: The minimum cost is $ ?for
minutes?
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
this is a quadratic equation.
replace n with x to get:
c(x) = 1.2x^2 - 24x + 690
this is in standard form where:
a = coefficient of x^2 term = 1.2
b = coefficient of x term = -24
c = constant term = 690
the minimum point of this equation will be when x = -b/(2a)
that becomes when x = -(-24)/(2*1.2) = 24/2.4 = 10
when x = 10, 1.2x^2 - 24x + 690 = 1.2*10^2 - 24*10 + 690 = 570.
the minimum point of the equation will be at the point (x,y) = (10,570).

here's the graph.

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