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at what price will the manufacturer sell the maximum number of drills?

A manufactureer determines that the number of drills it can sell is given by the formula D= -3p^2 + 174p - 310 where p is the price of the drills in dollars

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Vivian L. | Microsoft Word/Excel/Outlook, essay composition, math; I LOVE TO TEACHMicrosoft Word/Excel/Outlook, essay comp...
3.0 3.0 (1 lesson ratings) (1)
Hi Robert;
D= -3p2 + 174p - 310
Let's take the derivative and set it equal to zero.
The answer is $29.
This is the vertex of the downward parabola.  We know it is downward because 3p2 is negative.  The vertex is the point at which rate of change is zero.


Thanks Vivian My daughter asked me tonight this question and I could not remember how to solve it. Been a long time since I used parabola. She has not covered this in class yet and I could not find it in her book but it is on her midterm final in algebra 2.
Parviz F. | Mathematics professor at Community CollegesMathematics professor at Community Colle...
4.8 4.8 (4 lesson ratings) (4)
 What is the question?
    How many should be sold to have maximum profit.
       D(p) = -3p^2 + 174 p- 310
       D Maximum ( p) = -b/2a = -174/ -6 = 29
       D( 19) =  -3(19^2) +174*19 -310=


this was the next question but I assumed I needed to solve for p first which is $29. been a long time since I have used parabola. my daughter was studying for her final and had not covered this in class this semester. 
Robert J. | Certified High School AP Calculus and Physics TeacherCertified High School AP Calculus and Ph...
4.6 4.6 (13 lesson ratings) (13)
This is a parabola, which opens down. Therefore, at its vertex you get the maximum number of drills.
P = -b/(2a) = -174/(2(-3)) = $29 <==Answer