北京大学：《微观经济学》Chapter Nine Buying and Selling 购买和销售

Changing endowments x2 Changing the endowment 15002

Changing Endowments x2 x1 (1 ’,2 ’) (1 ”,2 ”) (1 ,2 ) Changing the endowment

Changing prices x2 p1X1+p2X2=p1o1+p202 Changing prices of the endowment p1x1+p2X2=p101+p202

Changing Prices x2 1 x1 2 p1 x1 + p2 x2 = p11 + p22 p1 x1 p2 x2 p1 1 p2 2 ' ' ' ' + =  +  Changing prices of the endowment

Changing prices x2 p1X1+p2X2=p1o1+p202 Budget set p1x1+p2x2=p1a1+p202

Changing Prices x2 1 x1 2 p1 x1 + p2 x2 = p11 + p22 p1 x1 p2 x2 p1 1 p2 2 ' ' ' ' + =  +  Budget set

Changing prices The endowment point is always on x2 the budget constraint p1X1+p2X2=p1o1+p202 So price changes pivot the constraint about the endowment point p1x1+p2X2=p101+p202

Changing Prices x2 1 x1 2 p1 x1 + p2 x2 = p11 + p22 The endowment point is always on the budget constraint. p1 x1 p2 x2 p1 1 p2 2 ' ' ' ' + =  +  So price changes pivot the constraint about the endowment point

Net demand The constraint p1X1+p2x2=p1o1+p202 Is p1(x1-a1)+p2(x2-02)=0 That is, the sum of the values of a consumers net demands(净需求) s zero

Net Demand The constraint is That is, the sum of the values of a consumer’s net demands （净需求） is zero. p1 (x1 −1 ) + p2 (x2 −2 ) = 0. p1 x1 + p2 x2 = p11 + p22