改进解供求弹性的线段法

On improvement of the line segment method purporting to solve the elasticity of supply and demand

以往教学中对于线段法解线性供求弹性,用图解很繁琐。由于纵轴和横轴法供求弹性的基本思想是用价格变动(P0/△P)和产量变动(△Q/Q0)来解弹性,故借此思想在纵轴法中寻求使Q1=0从而使△Q/Q0=1的条件,在横轴法中寻求在使P0/△P=1的条件,最终取而代之图解可以获得简洁的效果。

When the elasticity of supply and demand equation needs to be resolved with vertical and horizontal axes, diagramming is explanatory. Since the essential concept of supply and demand elasticity with vertical and horizontal axes means a solution to the elasticity with price variable and quantity variable, P_1 in linear function thus determines the equation of Q_1=0, and even △Q/Q_0=1 according to the vertical axis method. In contrast, P1 becomes zero, and results in the equation of P_0/△P=1 according to the horizontal axis method. In this sense, the linear price elasticity of supply and demand can be solved without diagramming.