How fast is the cost per month changing when production is changing at the rate of 14 units per month and the production level is 60 units

Question

a manufacturer of handcrafted wine racks has determined that the cost to produce x units per month is given by C(x)= .3x^2+7000. How fast is the cost per month changing when production is changing at the rate of 14 units per month and the production level is 60 unit

Answer 1

dC/dX = .6X

 

dC = .6X dX

 

       = 0.6 * 60 * 14

 

       = 504