Algebraic Fractions

What is an algebraic fraction?

An algebraic fraction is a fraction that contains at least one algebraic expression (with a variable) such as $3x$ .
The expression can be in the numerator or the denominator or both.

Simplifying Algebraic Fractions

We can simplify algebraic fractions only when there is a multiplication operation between the algebraic factors in the numerator and the denominator, and there are no addition or subtraction operations.
Steps to simplify algebraic fractions:

The first step –
Attempt to factor out a common factor.
The second step –
Attempt to simplify using special product formulas.
The third step –
Attempt to factor by using a trinomial.

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Factoring algebraic fractions

How do you reduce algebraic fractions?

We will find the common factor that is most beneficial for us to extract.
If we do not find one, we will proceed to factorization using the formulas for shortened multiplication.
If we cannot use the formulas for shortened multiplication, we will proceed to factorization using trinomials.
We will simplify (only when there is multiplication between the terms unless the terms are in parentheses, in which case we will treat it as a single term).

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Addition and Subtraction of Algebraic Fractions

We will make all the denominators the same – we will reach a common denominator.
We will use factorization according to the methods we have learned.
Steps of the operation:

We will factor all the denominators.
We will multiply each numerator by the number it needs so that its denominator reaches the common denominator.
We will write the exercise with one denominator - the common denominator, and between the expressions in the numerators, we will keep the arithmetic operations as in the original exercise.
After opening parentheses, we might encounter another expression that we need to factor. We will factor it and see if we can simplify.
We will get a regular fraction and solve it.

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Multiplication and Division of Algebraic Fractions

Steps to multiply algebraic fractions:

Let's try to factor out a common factor.
The common factor can be our variable or any constant number.
If factoring out a common factor is not enough, we will reduce using the formulas for the product of sums or using trinomials.
Let's find the domain of substitution:
We will set all the denominators we have to 0 and find the solutions.
The domain of substitution will be: x different from what makes the denominator zero.
Let's simplify the fractions.
We will multiply numerator by numerator and denominator by denominator as in a regular fraction.

Steps for dividing algebraic fractions:

We will turn the division exercise into a multiplication exercise in this way:
We will leave the first fraction as it is, change the division sign to a multiplication sign, and invert the fraction that comes after the division operation. That is, numerator in place of denominator and denominator in place of numerator.
We will follow the rules for multiplying algebraic fractions:
- We will try to factor out a common factor.
  The common factor can be our variable or any free number.
- If factoring out a common factor is not enough, we will decompose using the formulas for shortened multiplication and also using trinomials.
- We will find the domain of substitution:
  We will set all the denominators we have to 0 and find the solutions.
  The domain of substitution will be x different from what zeros the denominator.
- We will simplify the fractions.
- We will multiply numerator by numerator and denominator by denominator as in a regular fraction.

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Detailed explanation

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Test yourself on factorization and algebraic fractions!

Select the field of application of the following fraction:

$\frac{x}{16}$

Practice more now

Simplifying algebraic fractions

Exercise:
Simplify the following algebraic fraction:
$\frac{4x+2}{2x}$

Solution:
First, we factor out the common factor $4$ in the numerator and get:
$\frac{4(x+1)}{2x}$
Now we simplify the $4$ by $2$ and get:
$\frac{2(x+1)}{x}$

Another exercise:
Simplify the following algebraic fraction:
$\frac{x+10}{20}$

Solution:
The fraction cannot be simplified because $x$ is not involved in multiplication but in addition.

Addition and subtraction of algebraic fractions

Exercise:
$\frac{1}{x^2-25}+\frac{1}{x^2-10x+25}=$

Let's factor all the denominators:
$\frac{1}{(x-5)(x+5)}+\frac{1}{(x-5)^2}=$
It is advisable to write down the common denominator in front of us, so it will be easier to know what to multiply each numerator by:
$(x+5) (x-5)^2$
We will multiply each numerator by what it needs so that its denominator reaches the common denominator, write the exercise with one denominator and get:
$\frac{x-5+x+5}{(x+5)(x-5)^2}=$
Combine terms in the numerator and get
$\frac{2x}{(x+5)(x-5)^2}$
This is the final answer.

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Test your knowledge

Question 1

Select the domain of the following fraction:

$\frac{8+x}{5}$

Question 2

Select the the domain of the following fraction:

$\frac{6}{x}$

Question 3

Select the field of application of the following fraction:

$\frac{3}{x+2}$

Examples with solutions for Algebraic Fractions

Exercise #1

Select the domain of the following fraction:

$\frac{8+x}{5}$

Video Solution

Step-by-Step Solution

The domain depends on the denominator and we can see that there is no variable in the denominator.

Therefore, the domain is all numbers.

Answer

All numbers

Exercise #2

Select the the domain of the following fraction:

$\frac{6}{x}$

Video Solution

Step-by-Step Solution

The domain of a fraction depends on the denominator.

Since you cannot divide by zero, the denominator of a fraction cannot equal zero.

Therefore, for the fraction $\frac{6}{x}$ , the domain is "All numbers except 0," since the denominator cannot equal zero.

In other words, the domain is:

$x\ne0$

Answer

All numbers except 0

Exercise #3

Determine if the simplification below is correct:

$\frac{5\cdot8}{8\cdot3}=\frac{5}{3}$

Video Solution

Step-by-Step Solution

Let's consider the fraction and break it down into two multiplication exercises:

$\frac{8}{8}\times\frac{5}{3}$

We simplify:

$1\times\frac{5}{3}=\frac{5}{3}$

Answer

Correct

Exercise #4

Determine if the simplification shown below is correct:

$\frac{7}{7\cdot8}=8$

Video Solution

Step-by-Step Solution

Let's consider the fraction and break it down into two multiplication exercises:

$\frac{7}{7}\times\frac{1}{8}$

We simplify:

$1\times\frac{1}{8}=\frac{1}{8}$

Therefore, the described simplification is false.

Answer

Incorrect

Exercise #5

Determine if the simplification below is correct:

$\frac{4\cdot8}{4}=\frac{1}{8}$

Video Solution

Step-by-Step Solution

We will divide the fraction exercise into two multiplication exercises:

$\frac{4}{4}\times\frac{8}{1}=$

We simplify:

$1\times\frac{8}{1}=8$

Therefore, the described simplification is false.

Answer

Incorrect

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