Marginal Cost

The marginal cost is the derivative of the cost function.

Example

Zoe, monopolist of the lemonade market on her street, faces the following production costs

$$ C ( Q ) = 2 Q $$

Her marginal cost is

$$ MC ( Q ) = \frac{d C ( Q )}{d Q} = 2 $$

It costs Zoe $2 to produce one additional liter of lemonade.

Question

Zoe's costs function is `C ( Q ) = 68 Q+ 84`.

What is her marginal cost of production?

Zoe's marginal cost are

$$ MC ( Q ) = \frac{d C ( Q )}{d Q} = 68 $$