In this paper,the relationship between uncertainty,firmsequivalent marginal costs and investment in the non perfect market is analyzed through financial option method,and the demand elasticity′s and firms market shares influences are discussed.

Based on the analysis of current safety investment in China, safety investment theory of marginal utility is discussed, which is used to determine total amounu of safety investment.

Starting with the progressive decreasing theory of marginal utility in traditional economy,this paper points out that the network economy is marginal utility progressive increasing economy and discusses the reason for it.

The marginal profit of breeding objective traits was calculated by WEU.

In the study, a bio economic model was integrated to estimate the marginal profits of the goal traits which includes reproduction longevity (litter), litter size born alive (pig/litter), body weight at birth (kg), daily gain (g/day), feed conversion efficiency (kg/kg), dressing rate (%), lean meat percentage (%) and meat quality index (%).

It has proved the purchase model of arbitrary demand,the functional relations between marginal benefit and purchase,and has showed how to define the quantities of purchase according to the marginal gross profit and how to handle the relations of profit and market share.

The model utilizes the equivalence relationship between marginal benefit and marginal damage to properly deal with the relationship between flood resources benefit and risk loss and determine the optimal utilizable quantity of flood resources for the purpose of maximizing the net benefit and minimizing the risk loss.

Under the condition of market economy and nation is the investment subject,in order to maximize energy-consuming benefit,we set up the energy space configuration model,which based on the equilibrium of marginal benefit;and set up th.