最新北大ceer 笔记19教学讲义PPT课件.ppt

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1、北大ceer笔记19StructureThecostminimizationproblemAveragecostsReturnstoscaleandtotalandaveragecostsShortrunandlongruncostsCostMinimizationAfirmisacost-minimizerifitproducesanygivenoutputlevely³0atsmallestpossibletotalcost.c(y)denotesthefirm’ssmallestpossibletotalcostforproducingyun

2、itsofoutput.c(y)isthefirm’stotalcostfunction（总成本函数）.TheCost-MinimizationProblemThelevelsx1*(w1,w2,y)andx1*(w1,w2,y)intheleast-costlyinputbundlearethefirm’sconditionaldemandsforinputs1and2（条件要素需求）.The(smallestpossible)totalcostforproducingyoutputunitsisthereforeConditionalInput

3、DemandsGivenw1,w2andy,howistheleastcostlyinputbundlelocated?Andhowisthetotalcostfunction（成本函数）computed?Iso-costLines（等成本线）Acurvethatcontainsalloftheinputbundlesthatcostthesameamountisaniso-costcurve.E.g.,givenw1andw2,the$100iso-costlinehastheequationIso-costLinesGenerally,give

4、nw1andw2,theequationofthe$ciso-costlineisi.e.Slopeis-w1/w2.Iso-costLinesc’ºw1x1+w2x2c”ºw1x1+w2x2c’

5、itsofoutput.Whichisthecheapest?f(x1,x2)ºy’TheCost-MinimizationProblemx1x2Allinputbundlesyieldingy’unitsofoutput.Whichisthecheapest?f(x1,x2)ºy’x1*x2*TheCost-MinimizationProblemx1x2f(x1,x2)ºy’x1*x2*Ataninteriorcost-mininputbundle:(a)TheCost-MinimizationProblemx1x2f(x1,x2)ºy’x

6、1*x2*Ataninteriorcost-mininputbundle:(a)and(b)slopeofisocost=slopeofisoquant;i.e.ACobb-DouglasExampleofCostMinimizationAfirm’sCobb-DouglasproductionfunctionisInputpricesarew1andw2.Whatarethefirm’sconditionalinputdemandfunctions?ACobb-DouglasExampleofCostMinimizationAttheinp

7、utbundle(x1*,x2*)whichminimizesthecostofproducingyoutputunits:(a)(b)andACobb-DouglasExampleofCostMinimization(a)(b)From(b),Nowsubstituteinto(a)togetSoisthefirm’sconditionaldemandforinput1.ACobb-DouglasExampleofCostMinimizationisthefirm’sconditionaldemandforinput2.SinceandA

8、Cobb-DouglasExampleofCostMinimizationSothecheapestinputbundle