浙江大学中级微观经济学ch2

1、无限的欲望预算约束选择问题),.,(21Lxxxx L),.2 , 1(Ll XLRX ), 0lxX00lxXyx, 1 , 0Xyx)1 (Xxyzx2x1Budget constraint isp1x1 + p2x2 = m.m /p2m /p1x2x1Budget constraint isp1x1 + p2x2 = m.m /p1Just affordablem /p2x2x1Budget constraint isp1x1 + p2x2 = m.m /p1Just affordableNot affordablem /p2x2x1Budget constraint isp1x1 +

2、 p2x2 = m.m /p1AffordableJust affordableNot affordablem /p2x2x1Budget constraint isp1x1 + p2x2 = m.m /p1BudgetSet the collection of all affordable bundles.m /p2x2x1p1x1 + p2x2 = m is x2 = -(p1/p2)x1 + m/p2 so slope（斜率）（斜率） is -p1/p2.m /p1BudgetSetm /p2xppxmp21212 x2x1+1-p1/p2Opp. cost of an extra un

3、it of commodity 1 is p1/p2 units foregone of commodity 2.x2x1Opp. cost of an extra unit of commodity 1 is p1/p2 units foregone of commodity 2. Opp. cost of an extra unit of commodity 2 is p2/p1 units foregone of commodity 1. -p2/p1+150m)2, 5(2xmpx 5 . 221ppk1/10pm51x预算线：斜率：154106252Originalbudget se

4、tx2x1Originalbudget setNew affordable consumptionchoicesx2x1Original andnew budgetconstraints areParallel（平行的（平行的，sameslope).Originalbudget setx2x1x2x1New, smallerbudget setConsumption bundlesthat are no longeraffordable.Old and newconstraintsare parallel.Originalbudget setx2x1m/p2m/p1m/p1”-p1/p2Ori

5、ginalbudget setx2x1m/p2m/p1m/p1”New affordable choicesBudget constraint pivots（转动）（转动）; slope flattens （平缓）（平缓）from -p1/p2 to -p1”/p2-p1/p2-p1”/p2x2x1mp2mp1p1x1 + p2x2 = mp1x1 + p2x2 = m/(1+t)mt p()11 mt p()12 x2x1mt p()12 mp2mt p()11 mp1Equivalent income lossismmtttm 11x2x1mt p()12 mp2mt p()11 mp1A

6、 uniform ad valoremsales tax levied at rate tis equivalent to an incometax levied at ratett1 .GF100100F + G = 100: before stamps.How about budget set after 40 food stamps issued？GF100100F + G = 100: before stamps.Budget set after 40 foodstamps issued.140The familys budgetset is enlarged.40(F-40) + G

7、 = 100 for F 40G=100 for F40GF100100F + G = 100: before stamps.Budget constraint after 40 food stamps issued.140120Budget constraint with black market trading.40u(F-40)+G=100 for F 40 即即 F+G=140uF+G=100+0.5 (40-F) for F40 即即 1.5F+G=120 GF100100F + G = 100: before stamps.Budget constraint after 40 fo

8、od stamps issued.140120Black market trading makes the budget set larger again.40 xy现金方案现金方案购物券方案购物券方案xym = $1005010020Slope = - 2 / 1 = - 2 (p1=2, p2=1)Slope = - 1/ 1 = - 1 (p1=1, p2=1)80 x2x1m = $1005010020Slope = - 2 / 1 = - 2 (p1=2, p2=1)Slope = - 1/ 1 = - 1 (p1=1, p2=1)80 x2x1m = $100501002080 x2x1Budget SetBudget Constraintx2x1Budget SetBudget Constraint10Budget constraints slope is-p1/p2 = -(-2)/1 = +2x2x1x2 = 2x1 + 1010 x2x1 Budget set is all bundles f