对于某些复杂的计算题目,巧用“换元”往往可以化繁为简,解题速度快,计算量不大,还不易出错,其方法是把一个数学式子或其中的一部分看作一个整体,用一个中间变量(即辅助元)去代换,从而简化式子结构,使问题易于解决,习惯上叫换元法.学生掌握此法实属必要.初中数学中,它主要应用于如下两个方面一、计算妙求值 For some complex calculation topics, the use of “for yuan ” can often simplify, solve problems faster, less computational complexity is not easy to make mistakes, the method is to put a mathematical formula or part of it As a whole, with an intermediate variable (that is, auxiliary elements) to replace, thus simplifying the substructure, the problem is easy to solve, used to call the metamorphic method. Students master this method is necessary. In the following two aspects, calculate the coup value