用图形来衡量竞争企业的利 measuring Profit in the Graph for the competitive Firm 竞争市场中的供给 有员企业 A Firm with Losses Supply in a Competitive Market 市场供给等于市场中各个企业 供给量的总和。 P = ARE MR Market supply equals the sum of the quantities supplied by the individual firms in the market mm小化m 短期:有固定数目企业的市场 短期:有固定数目企业的市场 The Short Run: Market Supply The Short Run: Market Supply with a Fixed number of firms with a Fixed number of firms ◆在任何一种既定价格上,每个企业供给 个删鱼业 使边际成本等于价格的产量。 dual Firm Supply For any given price, each firm supplies a Supply quantity of output so that its marginal cost equals price. s2.00 来线给曲线反应了个别企业的边际成 The market supply curve reflects the individual firms'marginal cost curves 100,000200000 (firm) 长期:有进入和退出的市场供给 长期:有进入和退出的市场供给 The Long Run: Market Supply The Long Run: Market Supply with Entry and Exit with Entry and Exit ◆企业将进入或退出市场,直到利润被推向零。 m's Zero-profit Condition Firms will enter or exit the market until profit is driven to zero ◆在长期,价格等于平均总成本的最小值。 In the long run, price equals the minimum of average total cost. ◆长期市场供给曲线是一条在此价格上的水平线 The long- run market supply curve is horizonta at this price. (firm6 31 亏损 Loss 用图形来衡量竞争企业的利润 Measuring Profit in the Graph for the Competitive Firm... 0 Quantity Price P = AR = MR MC ATC P Q 亏损最小化产量 Loss-minimizing quantity ATC b. 有亏损企业 A Firm with Losses 32 竞争市场中的供给 Supply in a Competitive Market 市场供给等于市场中各个企业 供给量的总和。 Market supply equals the sum of the quantities supplied by the individual firms in the market. 33 短期：有固定数目企业的市场 The Short Run: Market Supply with a Fixed Number of Firms ‹在任何一种既定价格上，每个企业供给 使边际成本等于价格的产量。 For any given price, each firm supplies a quantity of output so that its marginal cost equals price. ‹市场供给曲线反应了个别企业的边际成 本曲线。 The market supply curve reflects the individual firms’ marginal cost curves. 34 短期：有固定数目企业的市场 The Short Run: Market Supply with a Fixed Number of Firms... (a) 个别企业供给 Individual Firm Supply Quantity (firm) 0 Price (b) 市场供给 Market Supply Quantity (market) Price 0 MC Supply 1.00 $2.00 100 200 1.00 $2.00 100,000 200,000 35 长期：有进入和退出的市场供给 The Long Run: Market Supply with Entry and Exit ‹企业将进入或退出市场，直到利润被推向零。 Firms will enter or exit the market until profit is driven to zero. ‹在长期，价格等于平均总成本的最小值。 In the long run, price equals the minimum of average total cost. ‹长期市场供给曲线是一条在此价格上的水平线 The long-run market supply curve is horizontal at this price. 36 长期：有进入和退出的市场供给 The Long Run: Market Supply with Entry and Exit... (a) 企业的零利润条件 Firm’s Zero-Profit Condition 数量（企业） Quantity (firm) 0 价格 Price P = ATC的最小值 P = minimum ATC (b) 市场供给 Market Supply 数量（市场） Quantity (market) 价格 Price 0 供给 Supply MC ATC