Variables in Algebraic Expressions

šŸ†Practice algebraic expressions

When a problem is presented to us in writing, we can convert it into mathematical language (also called algebraic language) by transforming it into an algebraic expression. But what are algebraic expressions?

Variable: This is a letter that represents a numerical value, for example X X or Y Y . This letter refers to an unknown numerical value that we must work out. For example: if X+5=8 X+5=8 , then we can conclude that the numerical value of X X is 3 3 .

An algebraic expression is a combination of numbers and letters (representing unknown numbers) that includes operations such as addition, subtraction, multiplication, division, etc.

Each element of an algebraic expression is called an algebraic term, be it a variable, a constant, or a combination of a coefficient and one or more variables. If the expression contains only one term, it is known as a monomial, while those that contain two or more terms are polynomials.

There is no limitation to the amount of constant numbers, unknown variables, or operations that can appear in an algebraic expression. In addition, there does not always have to be a variable in the algebraic expression, although it will always have a certain numerical value.

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Test yourself on algebraic expressions!

einstein

Are the expressions the same or not?

\( 18x \)

\( 2+9x \)

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Examples of Algebraic Expressions

Let's take a look at some examples of algebraic expressions without variables:

4+74+7

93 \frac{9}{3}

3āˆ’23-2

2Ɨ8 2\times8

Here we can see that all of the expressions are composed of numbers and, since there are no unknown variables, we can calculate the result by simply performing the operations.

4+7=11 4+7 =11

93=3 \frac{9}{3}=3

3āˆ’2=1 3-2=1

2Ɨ8=16 2\times8=16


Now, let's look at some examples with variables:

X+5 X + 5

Xāˆ’Y X-Y

AƗ12 A\times\frac{1}{2}

X2+6 X^2+6

In this case, the examples include numbers, unknown variables (represented by letters), and mathematical operations (addition, subtraction, multiplication, division, etc.).


Exercises: Variables in Algebraic Expressions

Exercise 1

Find the algebraic expression that corresponds to the number of squares in the nth figure.

algebraic expressions corresponding to the number of squares

Solution:

Numbers of squares n

The first figure is formed from 11 square.

The second figure is formed from 44 squares, which can be expressed as 22 by 22.

The third figure is formed from 99 squares, which can be represented as 33 by 33.

Following this pattern, we can work out that the nth figure will be formed from nƗn=n2 n \times n = nĀ² squares.

Answer:

n2nĀ²


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Exercise 2

Find the algebraic expression that describes the number of circles in the figure n n .

Exercise 2 Assignment

Solution:

In figure 1 (n=1) (n=1) there are 6āˆ’1=56-1= 5 circles.

In figure 2 (n=2) (n=2) there are 6āˆ’2=46-2=4 circles.

In figure 3 (n=3) (n=3) there are 6āˆ’3=36-3=3 circles.

In figure 4 (n=4) (n=4) there are 6āˆ’4=26-4=2 circles.

Following this pattern, we can work out that there will be 6āˆ’n 6-n circles in the nth figure.

Answer:

6āˆ’n 6-n


Exercise 3

Simplify the following expression:

35m+9nāˆ’48m+52n 35m+9n-48m+52n

Solution:

35m+9nāˆ’48m+52n= 35m+9n-48m+52n=

First, we group like terms together.

35māˆ’48m+9n+52n= 35m-48m+9n+52n=

Then, simplify m m .

āˆ’13m+9n+52n= -13m+9n+52n=

Finally, simplify n n .

āˆ’13m+61n= -13m+61n=

61nāˆ’13m 61n-13m

Answer:

61nāˆ’13m 61n-13m


Do you know what the answer is?

Exercise 4

Simplify the following expression:

47x+57y+34x+89y\frac{4}{7}x+\frac{5}{7}y+\frac{3}{4}x+\frac{8}{9}y

Solution:

The like terms are grouped together and the fraction operations are performed.

47x+34x+57y+89y= \frac{4}{7}x+\frac{3}{4}x+\frac{5}{7}y+\frac{8}{9}y=

4Ɨ4+3Ɨ77Ɨ4x+5Ɨ9+7Ɨ87Ɨ9y= \frac{4\times4+3\times7}{7\times4}x+\frac{5\times9+7\times8}{7\times9}y=

16+2128x+45+5668y= \frac{16+21}{28}x+\frac{45+56}{68}y=

3728x+10168y= \frac{37}{28}x+\frac{101}{68}y=

1928x+13868y 1\frac{9}{28}x+1\frac{38}{68}y

Answer:

1928x+13868y 1\frac{9}{28}x+1\frac{38}{68}y


Exercise 5

Simplify the expression:

3baā‹…138a+58b+418m+910a+23m 3\frac{b}{a}\cdot1\frac{3}{8}a+\frac{5}{8}b+\frac{4}{18}m+\frac{9}{10}a+\frac{2}{3}m

Solution:

Here, the multiplication is performed and then the like terms are simplified.

3baā‹…138a+58b+418m+910a+23m 3\frac{b}{a}\cdot1\frac{3}{8}a+\frac{5}{8}b+\frac{4}{18}m+\frac{9}{10}a+\frac{2}{3}m

=2baā‹…(8+3)8a+88b+910a+418m+23m =\frac{2b}{a}\cdot\frac{\left(8+3\right)}{8}a+\frac{8}{8}b+\frac{9}{10}a+\frac{4}{18}m+\frac{2}{3}m

=3ā‹…118ā‹…a+58b+910a+4+2ā‹…618m =\frac{3\cdot11}{8\cdot a}+\frac{5}{8}b+\frac{9}{10}a+\frac{4+2\cdot6}{18}m

=338b+58b+910a+1618m =\frac{33}{8}b+\frac{5}{8}b+\frac{9}{10}a+\frac{16}{18}m

=33+58b+910a+89m=388b+910a+89m =\frac{33+5}{8}b+\frac{9}{10}a+\frac{8}{9}m=\frac{38}{8}b+\frac{9}{10}a+\frac{8}{9}m

=434b+910a+89m =4\frac{3}{4}b+\frac{9}{10}a+\frac{8}{9}m

Answer:

=434b+910a+89m =4\frac{3}{4}b+\frac{9}{10}a+\frac{8}{9}m


Check your understanding

Review Questions

What is a 'variable' in mathematics?

A variable is an unknown number.


How is a variable represented?

Variables are represented by a symbol, usually a letter of the alphabet such as XX or YY although Greek letters are also often used.


Are there any other names for variables?

Yes, sometimes they are also referred to as 'unknowns' or 'literals'.


If you are interested in this article, you may also be interested in the following articles:

On the Tutorela website you will find a variety of other useful mathematics articles!


How many exercises should I practice?

Since each student learns at a different pace, the answer to this question depends on you.
The important thing is that you are aware of your level and therefore whether or not you need to practice the formulas more.
That said, it is recommended that you do 10 basic and intermediate level exercises in order to learn a single basic formula.


Do you think you will be able to solve it?

Examples with solutions for Algebraic Expressions

Exercise #1

18xāˆ’7+4xāˆ’9āˆ’8x=? 18x-7+4x-9-8x=\text{?}

Video Solution

Step-by-Step Solution

To solve the exercise, we will reorder the numbers using the substitution property.

18xāˆ’8x+4xāˆ’7āˆ’9= 18x-8x+4x-7-9=

To continue, let's remember an important rule:

1. It is impossible to add or subtract numbers with variables.

That is, we cannot subtract 7 from 8X, for example...

We solve according to the order of arithmetic operations, from left to right:

18xāˆ’8x=10x 18x-8x=10x 10x+4x=14x 10x+4x=14x āˆ’7āˆ’9=āˆ’16 -7-9=-16 Remember, these two numbers cannot be added or subtracted, so the result is:

14xāˆ’16 14x-16

Answer

14xāˆ’16 14x-16

Exercise #2

7.3ā‹…4a+2.3+8a=? 7.3\cdot4a+2.3+8a=\text{?}

Video Solution

Step-by-Step Solution

It is important to remember that when we have numbers and variables, it is impossible to add or subtract them from each other.

We group the elements:

 

7.3Ɨ4a+2.3+8a= 7.3Ɨ4a + 2.3 + 8a =

29.2a + 2.3 + 8a = 

37.2a+2.3 37.2a + 2.3

 

And in this exercise, this is the solution!

You can continue looking for the value of a.

But in this case, there is no need.

Answer

37.2a+2.3 37.2a+2.3

Exercise #3

9m3m2Ɨ3m6= \frac{9m}{3m^2}\times\frac{3m}{6}=

Video Solution

Step-by-Step Solution

According to the laws of multiplication, we must first simplify everything into one exercise:

9mƗ3m3m2Ɨ6= \frac{9m\times3m}{3m^2\times6}=

We will simplify and get:

9m2m2Ɨ6= \frac{9m^2}{m^2\times6}=

We will simplify and get:

96= \frac{9}{6}=

We will factor the expression into a multiplication:

3Ɨ33Ɨ2= \frac{3\times3}{3\times2}=

We will simplify and get:

32=1.5 \frac{3}{2}=1.5

Answer

0.5m 0.5m

Exercise #4

Are the expressions the same or not?

18x 18x

2+9x 2+9x

Video Solution

Answer

No

Exercise #5

Are the expressions the same or not?

20x 20x

2Ɨ10x 2\times10x

Video Solution

Answer

Yes

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