The total cost C(x) in Rupees associated with the production of x units of an item is given by

C(x) = 0.007x3 – 0.003x2 + 15x + 4000.


Find the marginal cost when 17 units are produced.


Marginal cost (MC) is the rate of change of total cost with respect to output.

Then,


= 0.021x2 – 0.006x +15


So, when x = 17 then,


MC = 0.021(172) – 0.006(17) +15


= 0.021(289) – 0.102 + 15


= 20.967


Therefore, the marginal cost when 17 units are produced is Rs. 20.967.


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