近年来，含有多个变元的最值问题颇受人们的青睐，在各级各类试题中屡见不鲜．纵观８９年到９８年这十年来的高考试题，几乎每年都有这样的题型出现．由于这类问题变量繁多，相互之间的制约关系较难把握，导致许多同学面对此类问题时显得束手无策，在考试中频频失分，造成... In recent years, the problem of the most value with multiple variables has attracted people’s attention, and it is not uncommon in various types of questions at all levels. Looking at the high school exam questions from the years of 89 to 98, almost every year such questions appear. Due to the variety of variables in this type of problem, the relationship between them is more difficult to grasp, resulting in many students seem helpless when faced with such problems, frequent points in the exam, resulting in...