函数的定义域是指使函数有意义的自变量的取值范围,函数的定义域是函数的三要素之一,是函数的灵魂和核心,它是研究函数各种问题的基石.因此在研究与函数有关的各种问题时,必须树立“定义域优先”的观点,以先分析定义域来帮助解决问题,如果忽视了函数的定义域,就容易引起各种各样的错误. The domain of a function is defined as the range of values ​​that make the function meaningful. The domain of the function is one of the three elements of the function, and it is the soul and core of the function. It is the cornerstone for studying various problems of the function. Therefore, the When dealing with various issues related to functions, we must establish the concept of “domain-first” to analyze the domain of definitions first to help solve problems. If we ignore the domain of functions, it is easy to cause various errors.