# Brief calculus

posted by
**Kyle** on
.

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