为什么长期供给曲线会向右上方倾斜 Why the Long-Run Supply Curve 边际企业 Might Slope Upward Marginal Firm 些用于生产的资源数量可能是有限 边际企业是如果价格有任何下 Some resources used in production 降就退出市场的企业。 nay be available only in limited quantities The marginal firm is the firm ◆企业可能有不同的成本 that would exit the market if the Firms may have different costs price were any lower 总结 总结 Summary Summary ◆由于竞争企业是价格接受者,所以它的 ◆为了利润最大化,企业选择使边际收益等于边 收益与产 比例的。 To maximize profit a firm chooses the quantity Because a competitive firm is a price of output such that marginal revenue equals taker, its revenue is proportional to the marginal cost. amount of output it produces. ◆这也是使价格等于边际成本的产量。 ◆物品的价格等于企业的平均收益和边际 This is also the quantity at which price equals 收益 The price of the good equals both the ◆因此,企业的边际成本曲线是它的 firm's average revenue and its marginal Therefore, the firms marginal cost curve is its revenue supply curve. 总结 总结 Summary Summary °尔到毕均弯发同支翔宠牌在智墨物品价 ◆在有自由进入与退出的市场上,长期中企业利 润为零,所有企业在有效规模点生产。 In the short run when a firm cannot recover its fixed costs, the firm will choose to shut down In a market with free entry and exit, profits are mporarily if the price of the good is less than driven to zero in the long run and all firms average variable cost. produce at the efficient scale. ◆在长期中,企业能够回收其固定和可变成本,如果 ◆需求变动在不同时间范围之内有不同影响。 Changes in demand have different effects over In the long run when the firm can recover both different time he ron fixed and variable costs. it will choose to exit if the price is less than average total cost.8 43 为什么长期供给曲线会向右上方倾斜 Why the Long-Run Supply Curve Might Slope Upward ‹一些用于生产的资源数量可能是有限 的。 Some resources used in production may be available only in limited quantities. ‹企业可能有不同的成本。 Firms may have different costs. 44 边际企业 Marginal Firm 边际企业是如果价格有任何下 降就退出市场的企业。 The marginal firm is the firm that would exit the market if the price were any lower. 45 总结 Summary ‹由于竞争企业是价格接受者，所以它的 收益与产量是同比例的。 Because a competitive firm is a price taker, its revenue is proportional to the amount of output it produces. ‹物品的价格等于企业的平均收益和边际 收益。 The price of the good equals both the firm’s average revenue and its marginal revenue. 46 总结 Summary ‹为了利润最大化，企业选择使边际收益等于边 际成本的产量。 To maximize profit a firm chooses the quantity of output such that marginal revenue equals marginal cost. ‹这也是使价格等于边际成本的产量。 This is also the quantity at which price equals marginal cost. ‹因此，企业的边际成本曲线是它的供给曲线。 Therefore, the firm’s marginal cost curve is its supply curve. 47 总结 Summary ‹在短期中，企业不能回收其固定成本，如果物品价 格小于平均可变成本，企业将选择停止营业。 In the short run when a firm cannot recover its fixed costs, the firm will choose to shut down temporarily if the price of the good is less than average variable cost. ‹在长期中，企业能够回收其固定和可变成本，如果 价格小于平均总成本，企业将选择退出。 In the long run when the firm can recover both fixed and variable costs, it will choose to exit if the price is less than average total cost. 48 总结 Summary ‹在有自由进入与退出的市场上，长期中企业利 润为零，所有企业在有效规模点生产。 In a market with free entry and exit, profits are driven to zero in the long run and all firms produce at the efficient scale. ‹需求变动在不同时间范围之内有不同影响。 Changes in demand have different effects over different time horizons