中级微观管理学与利润管理知识分析课件

1、Chapter 9PROFIT MAXIMIZATIONCopyright 2005 by South-Western, a division of Thomson Learning. All rights reserved.1The Nature of FirmsA firm is an association of individuals who have organized themselves for the purpose of turning inputs into outputsDifferent individuals will provide different types

2、of inputsthe nature of the contractual relationship between the providers of inputs to a firm may be quite complicated2Contractual RelationshipsSome contracts between providers of inputs may be explicitmay specify hours, work details, or compensationOther arrangements will be more implicit in nature

3、decision-making authority or sharing of tasks3Modeling Firms BehaviorMost economists treat the firm as a single decision-making unitthe decisions are made by a single dictatorial manager who rationally pursues some goalusually profit-maximization4Profit MaximizationA profit-maximizing firm chooses b

4、oth its inputs and its outputs with the sole goal of achieving maximum economic profitsseeks to maximize the difference between total revenue and total economic costs5Profit MaximizationIf firms are strictly profit maximizers, they will make decisions in a “marginal” wayexamine the marginal profit o

5、btainable from producing one more unit of hiring one additional laborer6Output ChoiceTotal revenue for a firm is given byR(q) = p(q)qIn the production of q, certain economic costs are incurred C(q)Economic profits () are the difference between total revenue and total costs(q) = R(q) C(q) = p(q)q C(q

6、)7Output ChoiceThe necessary condition for choosing the level of q that maximizes profits can be found by setting the derivative of the function with respect to q equal to zero8Output ChoiceTo maximize economic profits, the firm should choose the output for which marginal revenue is equal to margina

7、l cost9Second-Order ConditionsMR = MC is only a necessary condition for profit maximizationFor sufficiency, it is also required that“marginal” profit must be decreasing at the optimal level of q10Profit Maximizationoutputrevenues & costsRCq*Profits are maximized when the slope ofthe revenue function

8、 is equal to the slope of the cost function The second-ordercondition prevents usfrom mistaking q0 asa maximumq011Marginal RevenueIf a firm can sell all it wishes without having any effect on market price, marginal revenue will be equal to priceIf a firm faces a downward-sloping demand curve, more o

9、utput can only be sold if the firm reduces the goods price12Marginal RevenueIf a firm faces a downward-sloping demand curve, marginal revenue will be a function of outputIf price falls as a firm increases output, marginal revenue will be less than price13Marginal RevenueSuppose that the demand curve

10、 for a sub sandwich isq = 100 10pSolving for price, we getp = -q/10 + 10This means that total revenue isR = pq = -q2/10 + 10qMarginal revenue will be given byMR = dR/dq = -q/5 + 1014Profit MaximizationTo determine the profit-maximizing output, we must know the firms costsIf subs can be produced at a

11、 constant average and marginal cost of $4, thenMR = MC-q/5 + 10 = 4q = 3015Marginal Revenue and ElasticityThe concept of marginal revenue is directly related to the elasticity of the demand curve facing the firmThe price elasticity of demand is equal to the percentage change in quantity that results

12、 from a one percent change in price16Marginal Revenue and ElasticityThis means thatif the demand curve slopes downward, eq,p 0 and MR pif the demand is elastic, eq,p -1 and marginal revenue will be positiveif the demand is infinitely elastic, eq,p = - and marginal revenue will equal price17Marginal

13、Revenue and Elasticityeq,p 0eq,p = -1MR = 0eq,p -1MR -1, MC 0As output increases beyond q1, totalrevenue decreases so MR SAC,profit 028Short-Run Supply by a Price-Taking FirmoutputpriceSMCSACSAVCp* = MRq*If the price risesto p*, the firmwill produce q*and 0q*p*29Short-Run Supply by a Price-Taking Fi

14、rmoutputpriceSMCSACSAVCp* = MRq*If the price falls to p*, the firm will produce q*q*p*Profit maximizationrequires that p = SMC and that SMCis upward-sloping 030Short-Run Supply by a Price-Taking FirmThe positively-sloped portion of the short-run marginal cost curve is the short-run supply curve for

15、a price-taking firmit shows how much the firm will produce at every possible market pricefirms will only operate in the short run as long as total revenue covers variable costthe firm will produce no output if p SAVC31Short-Run Supply by a Price-Taking FirmThus, the price-taking firms short-run supp

16、ly curve is the positively-sloped portion of the firms short-run marginal cost curve above the point of minimum average variable costfor prices below this level, the firms profit-maximizing decision is to shut down and produce no output32Short-Run Supply by a Price-Taking FirmoutputpriceSMCSACSAVCTh

17、e firms short-run supply curve is the SMC curve that is above SAVC33Short-Run SupplySuppose that the firms short-run total cost curve isSC(v,w,q,k) = vk1 + wq1/k1-/ where k1 is the level of capital held constant in the short runShort-run marginal cost is34Short-Run SupplyThe price-taking firm will m

18、aximize profit where p = SMCTherefore, quantity supplied will be35Short-Run SupplyTo find the firms shut-down price, we need to solve for SAVCSVC = wq1/k1-/SAVC = SVC/q = wq(1-)/k1-/SAVC SMC for all values of p1(p2,) (p1,) The welfare gain to the firm of this price increase can be measured bywelfare

19、 gain = (p2,) - (p1,) 44Producer Surplus in the Short RunoutputpriceSMCp1q1If the market priceis p1, the firm will produce q1If the market pricerises to p2, the firm will produce q2p2q245The firms profits rise by the shaded areaProducer Surplus in the Short RunoutputpriceSMCp1q1p2q246Producer Surplu

20、s in the Short RunMathematically, we can use the envelope theorem results47Producer Surplus in the Short RunWe can measure how much the firm values the right to produce at the prevailing price relative to a situation where it would produce no output48Producer Surplus in the Short RunoutputpriceSMCp1

21、q1Suppose that the firms shutdown price is p0p049Producer Surplus in the Short RunThe extra profits available from facing a price of p1 are defined to be producer surplus50Producer surplus at a market price of p1 is the shaded areaProducer Surplus in the Short RunoutputpriceSMCp1q1p051Producer Surpl

22、us in the Short RunProducer surplus is the extra return that producers make by making transactions at the market price over and above what they would earn if nothing was producedthe area below the market price and above the supply curve52Producer Surplus in the Short RunBecause the firm produces no

23、output at the shutdown price, (p0,) = -vk1profits at the shutdown price are equal to the firms fixed costsThis implies thatproducer surplus = (p1,) - (p0,) = (p1,) (-vk1) = (p1,) + vk1producer surplus is equal to current profits plus short-run fixed costs53Profit Maximization and Input DemandA firms

24、 output is determined by the amount of inputs it chooses to employthe relationship between inputs and outputs is summarized by the production functionA firms economic profit can also be expressed as a function of inputs(k,l) = pq C(q) = pf(k,l) (vk + wl)54Profit Maximization and Input DemandThe firs

25、t-order conditions for a maximum are/k = pf/k v = 0/l = pf/l w = 0A profit-maximizing firm should hire any input up to the point at which its marginal contribution to revenues is equal to the marginal cost of hiring the input55Profit Maximization and Input DemandThese first-order conditions for prof

26、it maximization also imply cost minimizationthey imply that RTS = w/v56Profit Maximization and Input DemandTo ensure a true maximum, second-order conditions require thatkk = fkk 0ll = fll 0capital and labor must exhibit sufficiently diminishing marginal productivities so that marginal costs rise as

27、output expands57Input Demand FunctionsIn principle, the first-order conditions can be solved to yield input demand functionsCapital Demand = k(p,v,w)Labor Demand = l(p,v,w)These demand functions are unconditionalthey implicitly allow the firm to adjust its output to changing prices58Single-Input Cas

28、eWe expect l/w 0diminishing marginal productivity of laborThe first order condition for profit maximization was/l = pf/l w = 0Taking the total differential, we get59Single-Input CaseThis reduces toSolving further, we getSince fll 0, l/w 060Two-Input CaseFor the case of two (or more inputs), the stor

29、y is more complexif there is a decrease in w, there will not only be a change in l but also a change in k as a new cost-minimizing combination of inputs is chosenwhen k changes, the entire fl function changesBut, even in this case, l/w 061Two-Input CaseWhen w falls, two effects occursubstitution eff

30、ectif output is held constant, there will be a tendency for the firm to want to substitute l for k in the production processoutput effecta change in w will shift the firms expansion paththe firms cost curves will shift and a different output level will be chosen62Substitution Effectq0l per periodk p

31、er periodIf output is held constant at q0 and w falls, the firm will substitute l for k in the production processBecause of diminishing RTS along an isoquant, the substitution effect will always be negative63Output EffectOutputPriceA decline in w will lower the firms MCMCMCConsequently, the firm wil

32、l choose a new level of output that is higherPq0q164Output Effectq0l per periodk per periodThus, the output effect also implies a negative relationship between l and wOutput will rise to q1q165Cross-Price EffectsNo definite statement can be made about how capital usage responds to a wage changea fal

33、l in the wage will lead the firm to substitute away from capitalthe output effect will cause more capital to be demanded as the firm expands production66Substitution and Output EffectsWe have two concepts of demand for any inputthe conditional demand for labor, lc(v,w,q)the unconditional demand for

34、labor, l(p,v,w)At the profit-maximizing level of outputlc(v,w,q) = l(p,v,w)67Substitution and Output EffectsDifferentiation with respect to w yieldssubstitution effectoutput effecttotal effect68Important Points to Note:In order to maximize profits, the firm should choose to produce that output level

35、 for which the marginal revenue is equal to the marginal cost69Important Points to Note:If a firm is a price taker, its output decisions do not affect the price of its outputmarginal revenue is equal to priceIf the firm faces a downward-sloping demand for its output, marginal revenue will be less th

36、an price70Important Points to Note:Marginal revenue and the price elasticity of demand are related by the formula71Important Points to Note:The supply curve for a price-taking, profit-maximizing firm is given by the positively sloped portion of its marginal cost curve above the point of minimum aver

37、age variable cost (AVC)if price falls below minimum AVC, the firms profit-maximizing choice is to shut down and produce nothing72Important Points to Note:The firms reactions to the various prices it faces can be judged through use of its profit functionshows maximum profits for the firm given the pr

38、ice of its output, the prices of its inputs, and the production technology73Important Points to Note:The firms profit function yields particularly useful envelope resultsdifferentiation with respect to market price yields the supply functiondifferentiation with respect to any input price yields the

39、(inverse of) the demand function for that input74Important Points to Note:Short-run changes in market price result in changes in the firms short-run profitabilitythese can be measured graphically by changes in the size of producer surplusthe profit function can also be used to calculate changes in p

40、roducer surplus75Important Points to Note:Profit maximization provides a theory of the firms derived demand for inputsthe firm will hire any input up to the point at which the value of its marginal product is just equal to its per-unit market priceincreases in the price of an input will induce subst

41、itution and output effects that cause the firm to reduce hiring of that input76（第14讲）考场作文开拓文路能力分解层次(网友来稿)江苏省镇江中学 陈乃香说明：本系列稿共24讲，20XX年1月6日开始在资源上连载【要义解说】文章主旨确立以后，就应该恰当地分解层次，使几个层次构成一个有机的整体，形成一篇完整的文章。如何分解层次主要取决于表现主旨的需要。【策略解读】一般说来，记人叙事的文章常按时间顺序分解层次，写景状物的文章常按时间顺序、空间顺序分解层次；说明文根据说明对象的特点，可按时间顺序、空间顺序或逻辑顺序分解层次

42、；议论文主要根据“提出问题分析问题解决问题”顺序来分解层次。当然，分解层次不是一层不变的固定模式，而应该富于变化。文章的层次，也常常有些外在的形式：1小标题式。即围绕话题把一篇文章划分为几个相对独立的部分，再给它们加上一个简洁、恰当的小标题。如世界改变了模样四个小标题：寿命变“长”了、世界变“小”了、劳动变“轻”了、文明变“绿”了。 2序号式。序号式作文与小标题作文有相同的特点。序号可以是“一、二、三”，可以是“A、B、C”，也可以是“甲、乙、丙”从全文看，序号式干净、明快；但从题目上看，却看不出文章内容，只是标明了层次与部分。有时序号式作文，也适用于叙述性文章，为故事情节的展开，提供了明晰的

43、层次。 3总分式。如高考佳作人生也是一张答卷。开头：“人生就是一张答卷。它上面有选择题、填空题、判断题和问答题，但它又不同于一般的答卷。一般的答卷用手来书写，人生的答卷却要用行动来书写。”主体部分每段首句分别为：选择题是对人生进行正确的取舍，填空题是充实自己的人生，判断题是表明自己的人生态度，问答题是考验自己解决问题的能力。这份“试卷”设计得合理而且实在，每个人的人生都是不同的，这就意味着这份人生试卷的“答案是丰富多彩的”。分解层次，应追求作文美学的三个价值取向：一要匀称美。什么材料在前，什么材料在后，要合理安排；什么材料详写，什么材料略写，要通盘考虑。自然段是构成文章的基本单位，恰当划分自然

44、段，自然就成为分解层次的基本要求。该分段处就分段，不要老是开头、正文、结尾“三段式”，这种老套的层次显得呆板。二要波澜美。文章内容应该有张有弛，有起有伏，如波如澜。只有这样才能使文章起伏错落，一波三折，吸引读者。三要圆合美。文章的开头与结尾要遥相照应，把开头描写的事物或提出的问题，在结尾处用各种方式加以深化或回答，给人首尾圆合的感觉。【例文解剖】 话题：忙忙，不亦乐乎 忙，是人生中一个个步骤，每个人所忙的事务不同，但是不能是碌碌无为地白忙，要忙就忙得精彩，忙得不亦乐乎。 忙是问号。忙看似简单，但其中却大有学问。忙是人生中不可缺少的一部分，但是怎么才能忙出精彩，忙得不亦乐乎，却并不简单。人生如同一张地图，我们一直在自己的地图上行走，时不时我们眼前就出现一个十字路口，我们该向哪儿，面对那纵轴横轴相交的十