SOLUTION: bob owns a watch repair shop. he has found that the cost of operating his shop is given by c(x)=3x^2-168x+52, where x is the number of watches repaired. how many watches must he re

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Question 629201: bob owns a watch repair shop. he has found that the cost of operating his shop is given by c(x)=3x^2-168x+52, where x is the number of watches repaired. how many watches must he repair to have the lowest cost?
Answer by 303795(602) About Me  (Show Source):
You can put this solution on YOUR website!
The minimum cost will have a first derivative with a value of zero.
ie
c(x)=3x^2 - 168x + 52
c'(x) = 6x - 168
ie 6x - 168 = 0
6x = 168
x = 168/6
= 28