换元法是数学解题中的一种重要的思想方法,在中学数学中有着广泛的应用.在证明不等式时,根据题设条件,进行合理的代换,可以使字母之间的关系更清楚,还可以改变待证式的结构特征,为综合运用其它方法和有关知识创造条件.因此,常能起到化繁为简、化难为易的作用.下面通过具体的例? Redemption method is an important way of thinking in mathematical problem solving, which has a wide range of applications in high school mathematics.In the proof of inequality, according to the preconditions, reasonable substitution, you can make the relationship between letters more clearly , But also can change the characteristics of the structure to be probative, in order to create conditions for the comprehensive use of other methods and related knowledge, therefore, can often play the role of simplification, difficulty is easy.