9.5 : 垄断下的平均收益（AR）曲线和边际收益（MR）曲线

Average revenue is the revenue per unit sold, and the marginal revenue is the additional revenue earned from selling one more unit.

The AR and MR curves are downward-sloping.

In a monopoly, the demand curve is also the AR  curve because the monopolist sets the market price and the quantity sold. As the price is lowered to sell more units, the average revenue for each item sold aligns with the demand curve.

The relative steepness of the demand curve's slope indicates that the product's quantity demanded is not as highly responsive to price increases as more competitive markets. This is due to the lack of suitable substitutes.

To sell an additional unit, a firm must lower its price, making the MR curve steeper than the AR curve.

Additionally, total revenue is the overall income from selling goods, calculated by multiplying the quantity sold by the price per unit.

The TR curve initially rises at a decreasing rate, reaches a maximum, and then declines because to sell more, a monopolist must lower the price.