整式的运算是初中数学中一个非常重要的内容.换元法是解数学题时一种重要的解题方法.在整式运算的学习中,对一些较为复杂的题目,经常需要把某些结构相同的式子看成一个整体,用一个新的变量去代替它,从而使问题得以简化,使代数式的结构变的简单.换元法的实质就是转化,将生疏问题转化为熟悉问题,将未知条件转化为已知条件,将一个综合问题转化为几个基本问题.运用换元法的关键是构造元和设元,理论依据是等量代换.通过换元法,可以变换研究对象,使问题移至新对象的知识背 Integer arithmetic is a very important part in junior middle school mathematics.Transformation method is an important solution to mathematical problems.In the study of integer arithmetic, for some more complex topics, it is often necessary to make some structures the same Of the formula as a whole, with a new variable to replace it, so that the problem can be simplified so that the algebraic structure becomes simple. Substitution of the essence of the law is to transform the strange problem into a familiar problem, the unknown conditions Into known conditions, will be an integrated problem into a few basic problems. The key to using the yuan-changing method is to construct the yuan and set the yuan, the theoretical basis is equivalent substitution. By changing the yuan method, you can change the research object, so that the problem Move to the new subject’s knowledge back