解某些数学问题时,必须遵循先做什么,后做什么的原则,倘若不遵循这一原则,不是难解就是解错.下面举例说明.一、判断函数奇偶性时,先考虑函数定义域,后考虑函数f(x)是否满足f(-x)=f(x)或f(-x)=-f(x).【例1】判断函数f(x)=4-x2｜x+3｜-3的奇偶性.解:依题意有4-x2≥0｜x+3｜-3≠0- When solving certain mathematical problems, we must follow the principle of what to do first and then what to do. If you do not follow this principle, it is not difficult to solve or to solve the problem. Here is an example. First, when considering the function parity, consider the function domain. Then, consider whether the function f(x) satisfies f(-x)=f(x) or f(-x)=-f(x). [Example 1] Judging function f(x)=4-x2|x+ 3|-3 parity. Solution: There is 4-x2≥0|x+3|-3≠0-