用不等式求最值时,定值的确定是一个难点,也是相关高考题中经常设计的一个“坎”.它往往需要一定的灵活性或变形技巧.下面举例说明: When using the inequality to find the best value, the determination of the fixed value is a difficult point, and it is also a “can” often designed in related college entrance examination questions. It often requires a certain degree of flexibility or deformation techniques. The following examples illustrate: