也谈需求价格弹性的性质与总收益(总支出)的关系

在非线性条件下,需求曲线可以近似用函数Qd=kP-E表达,价格P取值在(0,e1/E)时,需求弹性Ed的大小决定需求曲线陡峭还是平坦.这时,Ed＞1的富有弹性的商品(奢侈品)需求曲线较平坦,而0＜Ed＜1的缺乏弹性的商品(必需品)需求曲线较陡峭,前者价格与总收益成反方向变动,即价格上升,总收益减少;价格下降,总收益增加.后者情形刚好相反.在线性条件下,只有两条需求曲线相交时(但不能相交于纵轴),需求弹性Ed的大小决定需求曲线陡峭还是平坦,Ed越大,需求曲线较平坦,Ed越小,需求曲线较陡峭.但价格与总收益的关系要分不同的情况具体分析.

On Relations Between Demand Prices And Total Income(Outcome) In Accordance With The Characterictics Of Price Elasticity

Under thenon-linear condition, when the demand curve can be expressed approximately with function Qd=kP -E and when, price P fetching value in((0,e 1/E ), the size of demand elasticity Ed determines whether the demand curve is precipitous or smooth. At this moment, goods whose Ed is more than 1, rich in elasticity (luxuary goods) its curve is relatively smoother, and those goods(necessities) whose Ed is less than 1, deficient in elasticity, its curve is relatively precipitous. The of former price and total income chage in reverse directions change, namely the price rises, the total income reduces, the price drops, the total income increases. The latter's situation is just the opposite. Under the linear condition, only when two demands curves are crossing (but can't be crossing in the axis of ordinates),the size of demand elasticity Ed determines whether the demand curve is precipitous or smooth, The bigger Ed is, the smouter is the demand curve is relatively smooth, the smaller Ed is, the demand curve is. But the relation between the price and total income should be analyzed in different situation.