二元函数极值计算中错解分析

Mistaken Solution Analysis of Minimax Value Calculation in Two-variable Function

选取典型例题，指出了二元函数极值计算中易犯的错误，如用拉格朗日乘数法求极值时，没有搞清辅助函数与原二元函数的关系，又如没有正确理解二元函数极值存在的充分条件，再如求二元函数的最值时没有注意边界点的讨论，针对这些常犯的错误，利用二阶微分或几何图形进行了分析，并给出了正确的解法．

Based on selected typical examples,this paper pointed out mistakes that often aremade in computing minimax value of two-variable function.For example,when computingminimax value with Lagrange's method of multiplies,the relation between assistant functionand primitive two-variable function is not comprehended,the sufficient condition of minimaxvalue existence in two-variable function is not understood correctly as well.More over,thediscussing of bound point in two-variable function maximzing is not took care,This paper anal-yses these mistakes with two order differential expression and geometrical graph,and gives thecorrect solutions.[