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title: What Is the Domain of a Function
localeTitle: 什么是函数的域
## 什么是函数的域
函数的域是自变量的完整可能值集。换句话说，域是所有可能的x值的集合，它将使函数“工作”，并将输出实际的y值。
例如，对于y = sqrt（x + 2） ，此函数的域为x> = -2 。
#### 更多信息：
[函数的域和范围](https://www.intmath.com/functions-and-graphs/2a-domain-and-range.php)