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# Domain of a function: Best way to find with Detailed Instructions

In math, the domain of a function is an important idea. It is a list of all of the possible inputs for a function. The set of all possible outputs from a function is called its range. To understand how a function works with its inputs and outputs, you need to know how to find the function’s domain.

In this blog post, NewTeach will show you step-by-step how to find the domain of a function. We will also show you examples and diagrams to help you better understand the idea. So if you’re a student or teacher looking for instructions on how to find the domain of a function, this blog article is for you!

## What is the domain of a function?

Before we look at how to find the domain of a function, it’s important to know what the domain of a function is. The set of all possible inputs for a function is called its domain. In other words, it is the set of all values that can be put into the function and will produce a result.

For example, the function f(x)=x+2 has a domain of all real numbers because you can plug in any real number and get a result. On the other hand, the domain of the function f(x)=1/x is all positive real numbers, because any negative real number will cause a division by zero error.

## How to find the domain of a function

The best way to find a domain will depend on the type of function. Here are the most important things you need to know about each type of function, which will be explained in the next section:

• A polynomial function whose denominator does not have any radicals or variables. The domain for this kind of function is all real numbers.
• A function with a fraction in which the denominator can change. To find the domain of this kind of function, set the bottom to zero and leave out the x value you get when you solve the equation.
• A function that has a variable inside a radical sign. Set the terms inside the radical sign to >0 and solve to find the values that work for x. This is how to find the domain of this type of function.
• The natural log is used in this function (ln). Set the terms in the parentheses to be greater than 0 and solve.

## Give the correct domain

Give the correct domain. The correct notation for the domain is easy to learn, but it is important to write it correctly to show the right answer and get full points on assignments and tests. Here are some important things to know about writing a function’s domain:

• The domain is written with an open bracket or parenthesis, then the two ends of the domain separated by a comma, and then a closed bracket or parenthesis. [-1,5] is an example. This means the domain is between -1 to 5.
• To show that a number is part of the domain, use brackets like [and]. So, in the example [-1, 5], -1 is part of the domain.
• Use a symbol like (and) inside parentheses to show that a number is not in the domain. In the example [-1,5), the number 5 is not in the domain. The domain stops short of 5 for no good reason, at 4.999. …
• Use “U,” which stands for “union,” to connect domain parts that are separated by a gap. [-1,5] U (5,10] is an example. This means that the range of the domain is from -1 to 10, but there is a gap at 5. This could be the result of a function whose denominator is “x – 5”, for example. If the domain has many gaps, you can use as many “U” symbols as you need.
• Use the signs for “infinity” and “negative infinity” to show that the domain goes on forever in both directions.
• With infinity symbols, you should always use ( ) and never [ ].

## Best Ways to find the Domain of Function

Here are some example can help you find the Domain of Function

### Situation f(x) = 2x/(x2 – 4)

For fractions with a variable in the denominator, set the denominator equal to 0. When figuring out the domain of a fractional function, you can’t divide by zero, so you have to leave out all the x-values that make the denominator equal to zero. So, make an equation for the denominator and set it equal to 0. This is what you do:

f(x) = 2x/(x2 – 4)

x2 – 4 = 0

(x – 2 )(x + 2) = 0

x ≠ (2, – 2). x = all real numbers except 2 and -2

### Situation Y =√(x-7)

Set the terms inside the radicand so that they are either greater than 0 or the same as 0. You can’t find the square root of a negative number, but you can do it for 0. So, make sure the terms inside the radicand are greater than or equal to 0. This is true for all roots with an even number, not just square roots. It does not, however, apply to roots with an odd number, because it is fine to have negatives under roots with an odd number. This is how:

x-7 ≧ 0

Isolate x on the left side of the equation by add 7 to both sides x ≧ 7

D = [7,∞)

### Situation f(x) = ln(x-8)

Set the terms inside the parentheses to more than zero. The natural log has to be a positive number, so set the terms inside the parentheses to be greater than zero. What you should do:

x – 8 > 0

x – 8 + 8 > 0 + 8. x > 8

Show that the domain for this equation is equal to all numbers greater than 8 until infinity

D = (8,∞)

In mathematics, the domain of a function is a very important idea. It is the set of all possible inputs for a given function, and it is essential to understanding how the function works in terms of its inputs and outputs. And we hope that this blog post has helped you figure out what a function’s domain is and how to find it.

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