《中学生数学》2014年第5期刊登了康宇老师的文章《学会运用换元法》,文中总结出了利用换元法注意的四个问题,即等价性、必要性、多样性、求简性.阅后受益匪浅.因此对换元法作了进一步的研究,总结出了学好换元法必须做到:“重分析、巧变形、抓特点、再换元”.下面举例说明,供读者参考. The fifth issue of “Mathematics for Secondary School Students” published the article “Learning to Use the Replacing Method” by Kang Yu in 2014, which summed up the four problems that pay attention to using the method of changing the yuan, that is, equivalence, necessity, diversity, Simple. Benefited from reading. So for the yuan made a further study, summed up the learning to change the law must be done: “reanalysis, clever deformation, grasping characteristics, and then change yuan.” The following example Description, for readers reference.