长期:有进入和退出的市场供给 为什么企业获得零利润还在经营? The Long Run: Market Supply Why Firms Stay in Business with Entry and Exit with Zero Profit? 程结束是,仍然留在市场中的企 ◆利润等于总收益减总成本。 Profit equals total revenue minus total cost. t the end of the process of entry and exit, firms that remain must be making zero economie profit. ◆总成本包括企业的所有机会成本。 Total cost includes all the opportunity costs of the firm. ◆是意学效与平均总成本被推向相时,进入与遇出 在零利润均衡时,企业的收益应该补偿所有者用于使 The process of entry exit ends only when price and average total cost are driven to equality In the zero-profit equilibrium, the firms revenue ◆竞争市场长期均衡一定是企业在其有效规模点运行 mpensates the owners for the time and money they Long- run equilibrium must have firms operating at ep the b their efficient seale ◆经济利润不同于会计利润 Economic profits differ from accounting profits. 需求的增加在短期内的影响 需求的增加在短期内和长期内的影响 Increase in Demand in the Increase in Demand in the short Run Short Run d(轴hnR ◆需求的增加在短期内提高价格并增加 An increase in demand raises price and quantity in the short run. ◆企业赚到正利润,因为价格现在高于 AN 长期供给 Firms earn profits because price now exceeds average total cost. 需求的增加在短期内和长期内的影响1「求的增加在短期内和长期内 Increase in Demand in the short run Increase in Demand in the short run and in the long run and in the Long Run (c)长期反应ong Frm企业 市场 Market 企业Fm Response 利润Pro 长期供给 金出H30器me 417 37 长期：有进入和退出的市场供给 The Long Run: Market Supply with Entry and Exit ‹当这种进入和退出过程结束是，仍然留在市场中的企 业必定得到零经济利润。 At the end of the process of entry and exit, firms that remain must be making zero economic profit. ‹只有当价格与平均总成本被推向相等时，进入与退出 过程才结束。 The process of entry & exit ends only when price and average total cost are driven to equality. ‹竞争市场长期均衡一定是企业在其有效规模点运行。 Long-run equilibrium must have firms operating at their efficient scale. 38 为什么企业获得零利润还在经营？ Why Firms Stay in Business with Zero Profit? ‹利润等于总收益减总成本。 Profit equals total revenue minus total cost. ‹总成本包括企业的所有机会成本。 Total cost includes all the opportunity costs of the firm. ‹在零利润均衡时，企业的收益应该补偿所有者用于使 企业维持的时间和金钱。 In the zero-profit equilibrium, the firm’s revenue compensates the owners for the time and money they expend to keep the business going. ‹经济利润不同于会计利润。 Economic profits differ from accounting profits. 39 需求的增加在短期内的影响 Increase in Demand in the Short Run ‹需求的增加在短期内提高价格并增加 数量。 An increase in demand raises price and quantity in the short run. ‹企业赚到正利润，因为价格现在高于 平均总成本。 Firms earn profits because price now exceeds average total cost. 40 需求的增加在短期内和长期内的影响 Increase in Demand in the Short Run and in the Long Run 企业Firm 市场Market Quantity (企业firm) 0 Price MC ATC P1 Quantity (市场market) Price 0 D1 P1 Q1 A S1 长期供给 Long-run supply (a)初始条件Initial Condition P 41 D2 需求的增加在短期内和长期内的影响 Increase in Demand in the Short Run and in the Long Run Firm企业 市场Market Quantity (企业firm) 0 Price MC ATC P1 Quantity (市场market) Price 0 D1 P1 Q1 A S1 长期供给 Long-run supply (b) 短期反应Short-Run Response Q2 B P2 P2 利润Profit 42 需求的增加在短期内和长期内的影响 Increase in Demand in the Short Run and in the Long Run 企业Firm 市场Market Quantity (firm) 0 Price MC ATC P1 Quantity (market) Price 0 D1 P1 Q1 A S1 长期供给 Long-run supply (c) 长期反应Long-Run Response D2 B Q2 P2 S2 C Q3