同济大学数学教研室主编的《高等数学》中关于换元积分法是这样叙述的:将复合函数的微分法反过来用于求不定积分,利用中间变量的代换,得到复合函数的积分法,称为换元积分法,简称为换元法。换元法通常分为两类,本文笔者主要对第一类换元积分法的应用给出另类理解。定理:(第一类换元积分法)设f(u)具有原函数,u=φ(x)可导,则有换元公式 Tongji University, Department of Mathematics editor of the “higher mathematics” on the yuan integral method is described as follows: the differential function of complex functions in reverse for uncertainty, the use of intermediate variable substitution, the composite function of the integral method, said Integral for the exchange method, referred to as the change method. The method of changing the yuan is usually divided into two categories, the author of this paper mainly gives an alternative understanding of the application of the first type of integral change method. Theorem: (the first kind of integral integral method) Let f (u) have the original function, u = φ (x) can be guided, there is a formula