# 微积分网课代修|预备微积分代写precalculus辅导|MATH113 Finding the Domain of a Function Defined by an Equation

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## 微积分网课代修|预备微积分代写precalculus辅导|Finding the Domain of a Function Defined by an Equation

In Functions and Function Notation, we were introduced to the concepts of domain and range. In this section, we will practice determining domains and ranges for specific functions. Keep in mind that, in determining domains and ranges, we need to consider what is physically possible or meaningful in real-world examples, such as tickets sales and year in the horror movie example above. We also need to consider what is mathematically permitted. For example, we cannot include any input value that leads us to take an even root of a negative number if the domain and range consist of real numbers. Or in a function expressed as a formula, we cannot include any input value in the domain that would lead us to divide by 0 .

We can visualize the domain as a “holding area” that contains “raw materials” for a “function machine” and the range as another “holding area” for the machine’s products. See Figure 2 .

## 微积分网课代修|预备微积分代写precalculus辅导|Finding the Domain of a Function Involving a Denominator

$$2-x=0-x \quad=-2 x=2$$

$$(-\infty, 2) \cup(2, \infty) \text {. }$$