Question

The marginal cost of producing the xth box of CDs is given by
9 − x/(x^2 + 1)^2.
The total cost to produce 2 boxes is $1,200. Find the total cost function
C(x).

I'm getting 9x-(1/(x^2 - 1))+1181.9 but i guess its wrong

Answer 1

forgot that pesky factor of 2.

∫-x/(x^2+1)^2 dx
is not 1/(x^2+1)
Check the derivative:
d/dx (x^2+1)^-1 = -2x(x^2+1)^-2

So,

∫9 − x/(x^2 + 1)^2 = 9x + 1/(2(x^2+1)^2)

Answer 2

sadofi