用反证法证明非周期函数,尽管都是利用等式f(x+T)=f(x).但具体做起来,不少中学生感到十分困难、不知从何入手,为此,本文介绍三种常用的证明方法。方法一直接应用周期函数的定义:对于函数y=f(x)、如果存在一个常数T≠0,使得当x取定义域内的每一个值时.都有f(x+T)=f(x)成立,那么函数y=f(x)叫做周期函数,我 The proof of non-periodic function by contradiction proves that although all use the equation f(x+T)=f(x). But concretely, many middle school students feel very difficult and do not know where to start. For this reason, this paper introduces three commonly used methods. The proof method. Method 1 directly applies the definition of the periodic function: For the function y=f(x), if there is a constant T≠0, when x takes every value in the domain, it has f(x+T)=f(x). ) is established, then the function y=f(x) is called periodic function, I