求多元函数最值问题,内涵丰富,方法灵活多变,技巧性强,难度大,解法没有规律性,且有些此类问题按常规方法求解更有难度.若利用题设条件、不等式性质、基本不等式及柯西不等式等连续放缩两次,将多元变量转化为少元变量或单元变量,并兼顾等号成立的条件来解答,可使思维简约,过程简捷.下面举例说明,旨在抛砖引玉.1.由题设条件和均值不等式连续放缩两次由题目直接或间接给出的条件和均值不等式连续放缩两次,将多元变量最值问题转化为一 Seeking the most value of multivariate function, rich in content, flexible method, skillful, difficult, solution is not regular, and some of these problems according to the conventional method to solve more difficult if the use of the problem conditions, the nature of inequality, the basic Inequality and Cauchy inequality and other continuous scaling twice, the multivariate variables into a few variables or unit variables, taking into account the conditions equal to the establishment of the answer, can make thinking simple, the process is simple. The following example, designed to start a discussion. 1 by the title conditions and mean inequality continuous scaling twice directly or indirectly given by the subject conditions and mean inequality continuous scaling twice, the multivariate maximum value problem into a