The per-copy cost of printing, marketing, and shipping x million copies of Danielle Tinne's new novel is given by the formula
C(x)=753-225x+3x^3
Find the number of copies that lead to the lower cost per copy, and find that minimum cost.

Question

The per-copy cost of printing, marketing, and shipping x million copies of Danielle Tinne's new novel is given by the formula
C(x)=753-225x+3x^3
Find the number of copies that lead to the lower cost per copy, and find that minimum cost.

radar · Answer

Take the derivative and set to 0, then apply max-min criteria.  select appropriate answer.

anonymous · Answer

please help me

radar · Answer

C(x) = 3x^3 - 225x + 753
C'(x) = 9x^2 - 225
Set to = 0 in accordance with max/min
9x^2 - 225 = 0
(3x + 15)(3x- 15= 0     Factor in accordance with the difference of two squares..
Solve for x getting x = 5 and x = -5     Only one can be the correct answer, your decision, use logic.