换元法是数学中常用的一种解题方法,在解题时我们会尽量减少未知元的个数使问题得解,而增元代换却反其道而行之,它往往在原题的基础上再增设几个元,以替换原已知条件,或改换命题方向,以达到求解之目的,现举例如下． Replacement method is a commonly used method of solving problems in mathematics. When solving a problem, we will try to reduce the number of unknown elements to solve the problem, while the substitution of the increasing yuan will be the opposite. It is often in the original title. On the basis of adding a few more elements, to replace the original known conditions, or change the direction of the proposition, in order to achieve the purpose of the solution, examples are as follows.