Questions on Algebra: Quadratic Equation answered by real tutors!

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Question 151427: I am very lost on this word problem. I don't even know where to begin. Could someone explain the steps to me?
A battery manufacturing plant spends C dollars per hour to produce "D" size batteries. An efficiency consultant has determined that C is related to the number of batteries produced per hour, x, according to the equation C(x)=0.01x^2 - 2.6x + 245. What number of batteries per hour minimizes the cost?
76, 130, 245 or 140 batteries.
Am I supposed to plug the number of batteries into the equation for x and solve? : I am very lost on this word problem. I don't even know where to begin. Could someone explain the steps to me?
A battery manufacturing plant spends C dollars per hour to produce "D" size batteries. An efficiency consultant has determined that C is related to the number of batteries produced per hour, x, according to the equation C(x)=0.01x^2 - 2.6x + 245. What number of batteries per hour minimizes the cost?
76, 130, 245 or 140 batteries.
Am I supposed to plug the number of batteries into the equation for x and solve?
Answer by scott8148(2776) About Me  (Show Source):
You can put this solution on YOUR website!
yes, you can substitute (plug in) to find the minimum value

another way is the fact that the minimum (or maximum) of a parabola (quadratic) is on the axis of symmetry

the general equation for the axis of symmetry is x=-b/(2a)

in this case __ x=-(-2.6)/[2(0.01)] __ x=130