新东方在线是新东方教育科技集团(NYSE:EDU)旗下专业的在线教育网站,是国内首批专业在线教育网站之一,依托新东方强大师资力量与教学资源,拥有中国先进的教学内容开发与制作团队,致... 学校首页
AP微观经济学重点(三)
7. market structure
(1) pure competitive market
记住完全竞争的几大特点:
many sellers sell idential products to many buyers;
no barriers, means firms free enter and exit;
price is taken from the market, and the firm can sell as many products as they want at this price;
demand is perfectly elastic (horizontal line),price = marginal revenue = average revenue
have allocative efficency (price = marginal cost)
利润最大化时是水平的demand curve 和上升的marginal cost 的相交点,向下和X轴相加的点是利润最大化时的产量;利润最大化时的产量那条垂直线和average total cost 相交,再做水平线与Y轴相交,则是平均成本点。由demand curve (代表selling price),平均成本价和产量,即可得出是economic profit (平均成本价在卖价下面),或是亏损(平均成本价在卖价上面)
记住:不论任何一种市场类型,要找利润最大化的产量,一定要先找到marginal revenue = marginal cost 的点,即MR 和MC的相交点,再向下与X轴相交于利润最大化时的产量
短期时几个重要点:
shut down position (price = variable cost)