Chapter13TheCostsofProductionTheMarketForcesofSupplyandDemandSupplyanddemandarethetwowordsthateconomistsusemostoften.Supplyanddemandaretheforcesthatmakemarketeconomieswork.Modernmicroeconomicsisaboutsupply,demand,andmarketequilibrium.13.1WhatAreCosts?AccordingtotheLawofSupply:Firmsarewillingtoproduceandsellagreaterquantityofagoodwhenthepriceofthegoodishigh.Thisresultsinasupplycurvethatslopesupward.TheFirm’sObjective:Theeconomicgoalofthefirmistomaximizeprofits.MaximumProfits13.1.1TotalRevenue,TotalCost,andProfitTotalRevenue

Theamountafirmreceivesforthesaleofitsoutput.

TotalCost

Themarketvalueoftheinputsafirmusesinproduction.

Profit

isthefirm’stotalrevenueminusitscost.Profit=Totalrevenue–Totalcost13.1.2CostsasOpportunityCostsThisdistinctionbetweenexplicitandimplicitcostshighlightsanimportantdifferencebetweenhoweconomistsandaccountantsanalyzeabusiness.Economistsareinterestedinstudyinghowfirmsmakeproductionandpricingdecisions.Becausethesedecisionsarebasedonbothexplicitandimplicitcosts,economistsincludebothwhenmeasuringafirm’scost.Bycontrast,accountantshavethejobofkeepingtrackofthemoneythatflowsintoandoutoffirms.Asaresult,theymeasuretheexplicitcostsbutoftenignoretheimplicitcost.13.1.4EconomicProfitversusAccountingProfitEconomistsmeasureafirm’seconomicprofitastotalrevenueminustotalcost,includingbothexplicitandimplicitcosts.Accountantsmeasureafirm’saccountingprofitasthefirm’stotalrevenueminusonlythefirm’sexplicitcosts.Whentotalrevenueexceedsbothexplicitandimplicitcosts,thefirmearnseconomicprofit.Economistsprofitissmallerthanaccountingprofit.Figure1EconomicversusAccountantsCopyright?2004South-WesternRevenueTotalopportunitycostsHowanEconomistViewsaFirmHowanAccountantViewsaFirmRevenueEconomicprofitImplicitcostsExplicitcostsExplicitcostsAccountingprofitEconomistsincludeallopportunitycostswhenanalyzingafirm,whereasaccountantmeasureonlyexplicitcosts.Therefore,economicprofitissmallerthanaccountingprofit.HowanEconomistViewsaFirmRevenueTotalopportunitycostsEconomicprofitHowanAccountantsViewsaFirmRevenueAccountingprofitImplicitcostsExplicitcostsExplicitcostsFigure1EconomistsversusAccountantsTable1AProductionFunctionandTotalCost:HungryHelen’sCookiesFactoryNumberofWorkersOutput(quantityofcookiesproducedperhour)MarginalProductofLaborCostofFactoryTotalCostofInputs(costoffactory+costofworkers)CostofWorkers00$30$0$30150301040290302050312030306041403040705150305080504030201013.2ProductionandCostsTheProductionFunctionTheProductionfunctionshowstherelationshipbetweenquantityofinputsusedtomakeagoodandthequantityofoutputofthatgood.MarginalProductTheMarginalproductofanyinputintheproductionprocessistheincreaseinoutputthatarisesfromanadditionalunitofthatinput.13.2TheProductionFunctionDiminishingMarginalProduct

Diminishingmarginalproductisthepropertywherebythemarginalproductofaninputdeclinesasthequantityoftheinputincreases.Example:Asmoreandmoreworkersarehiredatafirm,eachadditionalworkercontributeslessandlesstoproductionbecausethefirmhasalimitedamountofequipment.Aproductionfunctionshowstherelationshipbetweenthenumberofworkershiredandthequantityofoutputproduced.Herethenumberofworkershired(onthehorizontalaxis)isfromthefirstcolumninTable13-1,andthequantityofoutputproduced(ontheverticalaxis)isfromthesecondcolumn.Theproductionfunctiongetsflatterasthenumberofworkersincrease,whichreflectsdiminishingmarginalproduct.QuantityofOutput(cookiesperhour)NumberofWorkersHiredProductionfunction10234540206080100120140Figure2HungryHelen’sProductionFunction13.2.1TheProductionFunctionDiminishingMarginalProductTheslopeoftheproductionfunctionmeasuresthemarginalproductofaninput,suchasaworker.Whenthemarginalproductdeclines,theproductionfunctionbecomesflatter.13.2.2FromtheProductionFunctiontotheTotal-CostCurveTherelationshipbetweenthequantityafirmcanproduceanditscostsdeterminespricingdecisions.Thetotal-costcurveshowsthisrelationshipgraphically.Table1AProductionFunctionandTotalCost:HungryHelen’sCookiesFactoryNumberofWorkersOutput(quantityofcookiesproducedperhour)MarginalProductofLaborCostofFactoryTotalCostofInputs(costoffactory+costofworkers)CostofWorkers00$30$0$301503010402903020503120303060414030407051503050805040302010Atotal-costcurveshowstherelationshipbetweenthequantityofoutputproducedandtotalcostofproduction.Herethequantityofoutputproduced(onthehorizontalaxis)isfromthesecondcolumninTable13-1,andthetotalcost(ontheverticalaxis)isfromthesixthcolumn.Thetotal-costcurvegetssteeperasthequantityofoutputincreasesbecauseofdiminishingmarginalproduct.QuantityofOutput(cookiesperhour)TotalCostTotal-costcurve2004060801002010304060$807050120140Figure3HungryHelen’sTotal-CostCurveFromtheProductionFunctiontotheTotal-CostCurveNowcomparethetotal-costcurveinFigure3withtheproductionfunctioninFigure2.Thesetwocurvesareoppositesidesofthesamecoin.Thetotal-costcurvegetssteeperastheamountproducedrises,whereastheproductionfunctiongetsflatterasproductionrises.Thesechangesinslopeoccurforthesamereason.HighproductionofcookiesmeansthatHelen’skitcheniscrowdedwithmanyworkers.Becausethekitcheniscrowded,eachadditionalworkeraddslesstoproduction,reflectingdiminishingmarginalproduct.Therefore,theproductionfunctionisrelativelyflat.Butnowturnthislogicaround:Whenthekitcheniscrowded,producinganadditionalcookierequiresalotofadditionallaborandisthusverycostly.Therefore,whenthequantityproducedislarge,thetotal-costcurveisrelativelysteep.(Mankiw,thirdedition,p274)Costsofproductionmaybedividedintofixedcosts

and

variablecosts.Fixedcostsarethosecoststhatdonotvarywiththequantityofoutputproduced.Variablecostsarethosecoststhatdovarywiththequantityofoutputproduced.TotalcostsTotalFixedcosts(TFC)TotalVariablecosts(TVC)Totalcosts(TC)TC=TFC+TVC13.3.1FixedandVariableCostsTable2TheVariousMeasuresofCost:ThirstyThelma’sLemonadeStandQuantityofLemonade(glassesperhour)TotalCostVariableCostAverageFixedCostMarginalCost0$3.00$3.00$0.00---$0.300.50FixedCostAverageVariableCostAverageTotalCost13.303.000.30$3.00$0.30$3.3023.803.000.801.500.401.9034.503.001.501.000.501.50912.903.009.900.331.101.431015.003.0012.800.301.201.5079.303.006.300.430.901.3345.403.002.400.750.601.3556.503.003.500.600.701.3067.803.004.800.500.801.30811.003.008.000.381.001.380.700.901.101.301.501.701.902.10AveragecostsAveragecostscanbedeterminedbydividingthefirm’scostsbythequantityofoutputitproduces.Theaveragecostisthecostofeachtypicalunitofproduct.13.3.2AverageandMarginalCostsAveragecostsAverageFixedcosts(AFC)AverageVariablecosts(AVC)AverageTotalcosts(ATC)ATC=AFC+AVC13.3.2AverageandMarginalCostsAverageCosts

AFC==AVC==ATC==FixedcostQuantityFCQVariablecostQuantityVCQTotalcostQuantityTCQTable2TheVariousMeasuresofCost:ThirstyThelma’sLemonadeStandQuantityofLemonade(glassesperhour)TotalCostVariableCostAverageFixedCostMarginalCost0$3.00$3.00$0.00---$0.300.50FixedCostAverageVariableCostAverageTotalCost13.303.000.30$3.00$0.30$3.3023.803.000.801.500.401.9034.503.001.501.000.501.50912.903.009.900.331.101.431015.003.0012.800.301.201.5079.303.006.300.430.901.3345.403.002.400.750.601.3556.503.003.500.600.701.3067.803.004.800.500.801.30811.003.008.000.381.001.380.700.901.101.301.501.701.902.10Marginalcosts

Marginalcosts(MC)measurestheincreasesintotalcostthatarisesfromanextraunitofproduction.Marginalcosthelpsanswerthefollowingquestion:Howmuchdoesitcosttoproduceanadditionalunitofoutput?13.3.2AverageandMarginalCostsMarginalCosts

MC==

(changeintotalcost)△TC△Q(changeinquantity)

RelationshipsAmongCost&ProductionFunctionsAP&AVCareinverselyrelated.(ex:oneinput)AVC=(W

L)/Q=W/(Q/L)=W/APLAsAPLrises,AVCfallsMPandMCareinverselyrelated

MC=dTC/dQ=(W

dL)/dQ=W/(dQ/dL)=W/MPLAsMPLdeclines,MCrisesprod.functionscostfunctionsMPLLMCAP

AVC(Figure8.3onpage358)QQcostMarginalCost

ThirstyThelma’sLemonadeStandFigure4ThirstyThelma’sTotal-CostCurvesCopyright?2004South-WesternTotalCost$15.0014.0013.0012.0011.0010.009.008.007.006.005.004.003.002.001.00QuantityofOutput(glassesoflemonadeperhour)014327659810Total-costcurveHerethequantityofoutputproduced(onthehorizontalaxis)isfromthefirstcolumninTable13-2,andthetotalcost(ontheverticalaxis)isfromthesecondcolumn.AstheFigure13-3,thetotal-costcurvegetssteeperasthequantityofoutputincreasesbecauseofdiminishingmarginalproduct.TotalCostQuantityofOutput(glassesoflemonadeperhour)Total-CostCurve1023454.002.006.008.0010.0012.0014.00$15.00678910Figure4ThirtyThelma’sTotal-CostCurvesFigure5ThirstyThelma’sAverage-CostandMarginal-CostCurvesCopyright?2004South-WesternCosts$3.503.253.002.752.502.252.001.751.501.251.000.750.500.25QuantityofOutput(glassesoflemonadeperhour)014327659810MCATCAVCAFCCostsQuantityofOutput(glassesoflemonadeperhour)1023451.000.501.502.002.503.003.50678910MCAVCATCAFCFigure5ThirstyThelma’sAverage-CostandMarginal-CostCurvesFigure5ThirstyThelma’sAverage-CostandMarginal-CostCurveThisfigureshowstheaveragetotalcost(ATC),averagefixedcost(AFC),averagevariablecurve(AVC),andmarginalcost(MC)forThirstyThelma’sLemonadeStand.AllofthesecurvesareobtainedbygraphingthedatainTable13-2.Thesecostcurvesshowthreefeaturesthataretypicalofmanyfirms:(1)Marginalcostriseswiththequantityofoutput.(2)Theaverage-total-costcurveisU-shaped.(3)Themarginal-costcurvecrossestheaverage-total-costcurveattheminimumofaveragetotalcost.Marginalcostriseswiththeamountofoutputproduced.Thisreflectsthepropertyofdiminishingmarginalproduct.13.3.3CostCurvesandTheirShapesCostsQuantityofOutput(glassesoflemonadeperhour)1023451.000.501.502.002.503.003.50678910MCFigure5ThirstyThelma’sAverage-CostandMarginal-CostCurvesTheaveragetotal-costcurveisU-shaped.Atverylowlevelsofoutputaveragetotalcostishighbecausefixedcostisspreadoveronlyafewunits.Averagetotalcostdeclinesasoutputincrease.Averagetotalcoststartsrisingbecauseaveragevariablecostrisessubstantially.13.3.3CostCurvesandTheirShapesThebottomoftheU-shapedATCcurveoccursatthequantitythatminimizesaveragetotalcost.Thisquantityissometimescalledtheefficientscaleofthefirm.13.3.3CostCurvesandTheirShapesCostsQuantityofOutput(glassesoflemonadeperhour)1023451.000.501.502.002.503.003.50678910ATCFigure5ThirstyThelma’sAverage-CostandMarginal-CostCurvesRelationshipbetweenMarginalcostandAverageTotalCost.Whenevermarginalcostislessthanaveragetotalcost,averagetotalcostisfalling.Whenevermarginalcostisgreaterthanaveragetotalcost,averagetotalcostisrising.13.3.3CostCurvesandTheirShapesRelationshipbetweenMarginalcostandAverageTotalCost.Themarginal-costcurvecrossedtheaverage-total-costcurveattheefficientscale.Efficientscaleisthequantitythatminimizesaveragetotalcost.13.3.3CostCurvesandTheirShapesCostsQuantityofOutput(glassesoflemonadeperhour)1023451.000.501.502.002.503.003.50678910MCATCFigure5ThirstyThelma’sAverage-CostandMarginal-CostCurvesItisnowtimetoexaminetherelationshipsthatexistbetweenthedifferentmeasuresofcost.13.3.4TypicalCostCurvesQuantityofLemonade(glassesperhour)TotalCostVariableCostAverageFixedCostMarginalCost0$2.00$2.00$0.00---$1.000.80FixedCostAverageVariableCostAverageTotalCost13.002.001.00$2.00$1.00$3.0023.802.001.801.000.901.9034.402.002.400.670.801.4798.802.006.800.220.760.981010.202.008.200.200.821.0276.602.004.600.290.660.9544.802.002.800.500.701.2055.202.003.200.400.641.0465.802.003.800.330.630.9687.602.005.600.250.700.950.600.400.400.600.801.001.201.401111.802.009.800.180.891.071213.602.0011.600.170.971.141315.602.0013.600.151.051.201417.802.0015.800.141.131.271.601.802.002.20BigBob’sCostCurvesFigure6BigBob’sCostCurvesCopyright?2004South-Western(a)Total-CostCurve$18.0016.0014.0012.0010.008.006.004.00QuantityofOutput(bagelsperhour)TC42681412102.00TotalCost0(a)Total-CostCurve$18.002.004.006.008.0010.0012.0014.0016.00TotalCost02461081214QuantityofOutput(bagelsperhour)TCFigure6BibBob’sCostCurvesFigure6BigBob’sCostCurves(b)Marginal-andAverage-CostCurvesQuantityofOutput(bagelsperhour)Costs$3.002.502.001.501.000.5004268141210MCATCAVCAFC(b)Marginal-andAverage-CostCurves0.501.001.50Costs2.002.50$3.0062481014120QuantityofOutput(bagelsperhour)AFCAVCATCMCFigure6BibBob’sCostCurvesFigure6.BigBob’sCostCurve.Manyfirms,likeBigBob’sBin,experienceincreasingmarginalproductbeforediminishingmarginalproductand,therefore,havecostcurvesshapedlikethoseinthisfigure.Panel(a)showshowtotalcost(TC)dependsonthequantityproduced.Panel(b)showshowaveragetotalcost(ATC),averagefixedcost(AFC),averagevariablecurve(AVC),andmarginalcost(MC)dependsonthequantityproduced.Thesecurvesarederivedbygraphingthedatafromthetable.Noticethatmarginalcostandaveragevariablecostfallforawhilebeforestartingtorise.13.3.4TypicalCostCurvesThreeImportantPropertiesofCostCurvesMarginalcosteventuallyriseswiththequantityofoutput.Theaverage-total-costcurveisU-shaped.Themarginal-costcurvecrossestheaverage-total-costcurveattheminimumofaveragetotalcost13.4CostsintheShortrunandintheLongRunFormanyfirms,thedivisionoftotalcostsbetweenfixedandvariablecostsdependsonthetimehorizonbeingconsidered.Intheshortrun,somecostsarefixed.Inthelongrun,fixedcostsbecomevariablecosts.Becausemanycostsarefixedintheshortrunbutvariableinthelongrun,afirm’slong-runcostcurvesdifferfromitsshort-runcostcurves.Figure7AverageTotalCostintheShortandLongRunCopyright?2004South-WesternQuantityofCarsperDay0AverageTotalCost1,200$12,000ATC

inshortrunwithsmallfactoryATC

inshortrunwithmediumfactoryATC

inshortrunwithlargefactoryATC

inlongrunSourcesofIncreasingReturnstoScaleThesourcesofincreasingoutputperunitofinputwhenafirmgrowsincludetechnical,managerial,purchasing,marketingandfinancialeconomies.EconomiesandDiseconomiesofScale

Economiesofscale(increasingreturnstoscale)refertothepropertywherebylong-runaveragetotalcostfallsasthequantityofoutputincreases.Diseconomiesofscale(decreasingreturnstoscale)refertothepropertywherebylong-runaveragetotalcostrisesasthequantityofoutputincreases.

Constantreturnstoscalereferstothepropertywherebylong-runaveragetotalcoststaysthesameasthequantityofoutputincreases.Figure7AverageTotalCostintheShortandLongRunCopyright?2004South-WesternQuantityofCarsperDay0AverageTotalCost1,200$12,0001,00010,000EconomiesofscaleATC

inshortrunwithsmallfactoryATC

inshortrunwithmediumfactoryATC

inshortrunwithlargefactoryATC

inlongrunDiseconomiesofscaleConstantreturnstoscaleBecausefixedcostsarevariableinthelongrun,theaverage-total-costintheshortrundiffersfromtheaverage-total-costcurveinthelongrun.QuantityofCarsperDayAverageTotalCostATCinshortrunwithsmallfactory01,000$12,00010,0001,200ATCinshortrunwithmediumfactoryATCinshortrunwithlargefactoryConstantreturnstoscaleEconomiesofscaleDiseconomiesofscaleATCinlongrunFigure7AverageTotalCostintheShortandLongRunsTheterms“economiccosts,”thatinclude“normalprofits,”and“economicprofits”thatarenotincludedin“economicscosts”areoftenconfusing.Usingtheterm“excessoreconomicprofits”helps.Economistsclassifynormalprofitsascosts,sinceinthelongruntheownerofafirmwouldcloseitdownifanormalprofitwerenotbeingearned.Sinceanormalprofitisrequiredtokeeptheentrepreneuroperatingthefirm,anormalprofitisacost.Economicprofitsarenotcostsofproductionsincetheentrepreneurdoesnotrequirethegainingofaneconomicprofittokeepthefirmoperating.Ineconomics,costsarewhateverisrequiredtokeepafirmoperating.(McConnell,Economics,15edition,ch22productioncost.)SummaryThegoaloffirmsistomaximizeprofit,whichequalstotalrevenueminustotalcost.Whenanalyzingafirm’sbehavior,itisimportanttoincludealltheopportunitycostsofproduction.Someopportunitycostsareexplicitwhileotheropportunitycostsareimplicit.SummaryAfirm’scostsreflectitsproductionprocess.Atypicalfirm’sproductiongetsflatterasthequantityofinputincreases,displayingthepropertyofdiminishingmarginalproduct.Afirm’stotalcostsaredividedbetweenfixedandvariablecosts.Fixedcostsdonochangewhenthefirmaltersthequantityofoutputproduct,variablecostsdochangeasthefirmaltersquantityofoutputproduced.SummaryAveragetotalcostistotalcostdividedbythequantityofoutput.Marginalcostistheamountbywhichtotalcostwouldriseifoutputwereincreasedbyoneunit.Themarginalcostalwaysriseswiththequantityofoutput.Averagecostfirstfallsasoutputincreasesandthenrises.SummaryTheaverage-total-costcurveisU-shaped.Themarginal-costcurvealwayscrossestheaverage-total-costcurveattheminimumofATC.Afirm’scostsoftendependonthetimehorizonbeingconsidered.Inparticular,manycostsarefixedintheshortrunbutvariableinthelongrun.Mankiw-chapter13.ProblemandAnswer5.假定某廠商的邊際成本函數，且生產10單位產量時的總成本為1000。求:(1)固定成本的值。(2)總成本函數、總可變成本函數，以及平均成本函數、平均可變成本函數。(高鴻業《西方經濟學》第三版，第五章成本論)Mankiw-chapter13.ProblemandAnswerProblemandAnswer6.某公司用兩個工廠生產一種產品，其總成本函數為，其中Q1表示第一個工廠生產的產量，Q2表示第二個工廠生產的產量。求：當公司生產的產量為40時能夠使得公司生產成本最小的兩工廠的產量組合.(高鴻業《西方經濟學》第三版，第五章成本論)ProblemandAnswer7.已知生產函數；各要素價格分別為PA＝1，PL＝1，PK＝2；假定廠商處于短期生產，且。推導：該廠商短期生產的總成本函數和平均成本函數；總可變成本函數和平均可變成本函數；邊際成本函數。8.已知生產函數;當資本投入量K＝50時資本的總價格為500；勞動的價格PL＝5。求:(1)勞動的投入函數L=L(Q)(2)總成本函數、平均成本函數和邊際成本函數。(3)當產品價格P＝100時，廠商獲得最大利潤的產量和利潤各是多少？(高鴻業《西方經濟學》第三版，第五章成本論)5、已知生產函數Q=min(L,4K)。求：（1）當產量Q=32時，L與K值分別是多少？（2）如果生產要素的價格分別為PL=2，PK=5，則生產100單位產量時的最小成本是多少？解答：（1）生產函數Q=min(L,4K)表示該函數是一個固定投入比例的生產函數，所以，廠商進行生產時，總有Q=L=4K。因為已知產量Q=32，所以，相應地有L=32，K=8。（2）由Q=L=4K，且Q=100，可得：L=100，K=25

又因PL=2，PK=5，所以有：

C=PL·L+PK·K=2×100+5×25=325

既生產100單位產量的最小成本為325。6、已知生產函數為

求：（1）廠商長期生產的擴展線方程。（2）當PL=1，PK=1，Q=1000時，廠商實現最小成本的要素投入組合。解答：（1）（a）關于生產函數由最優要素組合的均衡條件

（2）關于生產函數由最優要素組合的均衡條件

（c）關于生產函數（d）關于生產函數Q=min(3L,K)。

由于該函數是固定投入比例的生產函數，既廠商的生產總有3L=K，所以，直接可以得到廠商長期生產的擴展方程為K=3L。（2）關于生產函數（b）關于生產函數。

（c）關于生產函數

（d）關于生產函數7、已知生產函數為判斷：（1）在長期生產中,該生產函數的規模報酬屬于哪一種?（2）在短期生產中,該生產函數是否受邊際報酬遞減的支配?解答：（1）所以，生產函數屬于規模報酬不變的生產函數。10.試用圖從短期總成本曲線推導出長期總成本曲線，并說明長期總成本曲線的經濟含義。11.試用圖從短期平均成本曲線推導長期平均成本曲線，并說明長期平均成本曲線的經濟含義。12.試用圖從短期邊際成本曲線推導長期邊際成本曲線，并說明長期邊際成本曲線的經濟含義。(高鴻業《西方經濟學》第三版，第五章成本論)ProblemandAnswerExerciseandAnswer3、為了實現既定成本條件下的最大產量或即定產量條件下的最小成本,如果企業處于

MRTSLK>

或者MRTSLK＜時,企業應該分別如何調整勞動和資本的投入量,以達到最優的要素組合?為什么?解答：要點如下：(1)研究給定條件下的產量最大化或成本最小化的分析工具是等產量曲線和等成本線。等產量曲線的斜率的絕對值可以用兩要素的邊際技術替代率MRTSLK

來表示,等成本線的斜率為-，即兩要素的相對價格。在幾何圖形的分析中，生產者追求既定約束條件下的產量最大化或成本最小化的均衡點都發生在等產量曲線和等成本線的相切點上,于是有生產者最優生產要素組合的均衡條件為：MRTSLK=

。其經濟含義為：在廠商的生產要素最優組合的均衡點上，廠商在生產中的兩要素的邊際技術替代比率(即MRTSLK)，即用一單位的勞動所替代的資本的數量，應該恰好等于該廠商能夠在市場用一單位的勞動去交換資本的數量(即)。(2)在MRTSLK>時，廠商對生產要素投入組合的調整,可以用圖1-19來說明。先看表示給定成本條件下的產量最大化的(a)圖。在(a)圖中的α點上有等產量曲線的斜率的絕對值大于等成本線斜率的絕對值，即MRTSLK>，且α點的要素投入組合為(L1,K1),相應的產量由等產量曲線Q1表示。但在成本給定(即等成本線AB給定)的條件下,a點的要素投入組合生產的產量并不是最大的。廠商應該從α點出發,沿著給定的表示約束條件的等成本線AB向均衡點E靠攏，比如說，由α點運動到α'點，則廠商就可以在不改變成本的條件下，將要素調整到(L2，K2)，從而達到更大的產量水平，此產量水平用過

α'點的等產量曲線Q2(虛線)來表示。很清楚，