1. Mathematical marginal cost refers to the increment of total cost per unit of newly produced products or purchased products. Marginal cost can be used to judge whether the increase or decrease of output is economical. When the enterprise has excess production capacity, as long as the sales unit price of the increased output is higher than the unit marginal cost, the profit of the enterprise will increase or the loss will decrease.

2. If this function is continuous, then the marginal cost is equivalent to the derivative of the function, that is, the slope; If this function is discrete, then the marginal cost is equivalent to an increasing sequence.