考研北师大微观经济学笔记Chapter

【考研笔记及资料】Part3RevisitingSupplyandDemandChapter6:ProfitMaximizationandSupplyChapter7:ConsumptionChoiceandDemandChapter6ProfitMaximizationandSupplyCostofProduction:Whichkindsofcostwouldbeincludedinproduction;theshapeofcostshape.ProfitMaximization:whatisprofit?MarginalprincipleleadstoprofitmaximizingbehaviorHowtochooseoutputandhowtosetpriceforafirmtomaximizeitsprofit?FixedCostsandVariableCostsTotalCost(TC)Totaleconomiccostofproduction,consistingoffixedandvariablecost.FixedCost(FC)Costthatdoesnotvarywiththelevelofoutput.VariableCost(VC)Costthatvariesasoutputvaries.FixedversusSunkCostWhetherthiskindofcostcanberecovered.CostofProductionMarginalCost(MC)Increaseincostresultingfromtheproductionofoneextraunitofoutput.AverageTotalCost(ATC)Firm’stotalcostdividedbyitslevelofoutput.AverageFixedCost(AFC)Fixedcostdividedbythelevelofoutput.AverageVariableCost(AVC)Variablecostdividedbythelevelofoutput.CostofProductionTheexpressionofmarginalcostTheexpressionofaveragetotalcostTheexpressionofAFCandAVCQTCATCQTCQVCMCQVCAVCQFCAFCCostOutputCostCurvesofaFirmTCVCFCCostOutputCostCurvesofaFirmATCAVCAFCMCProfitMaximizationProfitDifferencebetweentotalrevenueandtotalcostMaximizationofprofitleadstothemarginalprinciple)()()(qCqRq)()(qMCqMRCostOutputProfitMaximizationC(q)R(q)ABq*q0)(qDemandandMarginalRevenueRevenueisthequantityafirmsoldmultipliesthemarketpriceofthegood.MarginalrevenuecanbeexpressedbyqqPqR)()(qqPqPqMR)()()(PriceQuantityDemandCurveandMarginalRevenueDemandCurveMarginalRevenueq0021qCompetitiveFirmEachfirminacompetitiveindustrysellsonlyasmallfractionoftheentireindustrysalesThecompetitivefirmisapricetakerandknowsthatitsproductiondecisionwillhavenoeffectonthepriceoftheproduct.Thedemandcurvefacinganindividualcompetitivefirmisgivenbyahorizontalline.PriceQuantityDemandCurvefacedbyaCompetitiveFirmD0)(PqP0)(PqMR0)(PqARProfitMaximizationbyaCompetitiveFirmBecausethedemandcurvefacingacompetitivefirmishorizontal,sothatAperfectlycompetitivefirmshouldchooseitsoutputaccordingtothegeneralruleforprofitmaximizationsothatmarginalcostequalspricePqMR)(PMRqMC)(CostOutputCostCurvesofaFirmATCAVCAR=MR=PMCACompetitiveFirmMakingaPositiveProfitA*qCostOutputCostCurvesofaFirmATCAVCAR=MR=PMCACompetitiveFirmMakingaPositiveProfit*qCostOutputCostCurvesofaFirmATCAVCAR=MR=PMCACompetitiveFirmMakingaPositiveProfit*q1qCostOutputCostCurvesofaFirmATCAVCAR=MR=PMCACompetitiveFirmMakingaPositiveProfit*q2qOutputRuleIfafirmisproducinganyoutputatall,itshouldproduceatthelevelatwhichmarginalrevenueequalsmarginalcost.MCMRCostOutputCostCurvesofaFirmATCAVCMR=PMCACompetitiveFirmMakingaNegativeProfit*qCostOutputCostCurvesofaFirmATCAVCMR=PMCACompetitiveFirmMakingaNegativeProfit*qCostOutputCostCurvesofaFirmATCAVCMR=PMCACompetitiveFirmMakingaNegativeProfit*qCostOutputCostCurvesofaFirmATCAVCMR=PMCACompetitiveFirmMakingaNegativeProfit*qShut-DownRuleThefirmshouldshutdownifthepriceoftheproductislessthantheaverageeconomiccostofproductionattheprofit-maximizingoutput.0)(qProducerSurplusversusProfitSurplus:Sumoverallunitsproducedbyafirmofdifferencesbetweenmarketpriceofagoodandmarginalcostsofproduction.Profit:Differencebetweentotalrevenueandtotalcost.CostOutputCostCurvesofaFirmProfitAVCPMCVariableProfitforaFirm*qABCDCostOutputCostCurvesofaFirmSurplusAVCPMCProducerSurplusforaFirm*qABCDCostOutputATCAVCP=AVCMCTheShort-RunSupplyCurveforaCompetitiveFirmminqP1P21q2qPriceQuantityP=AVCTheShort-RunSupplyCurveforaCompetitiveFirmminqP1P21q2qTheCompetitiveFirm’sSupplyCurveAsupplycurveofafirmtellsushowmuchoutputitwillproduceateverypossibleprice.Thesupplycurvecanbeobtainedfromboththemarginalprincipleandtheshut-downrule.Thefirm’ssupplycurveistheportionofthemarginalcostcurvethatliesabovetheaverageeconomiccostcurve.