## Constant and Variable in Algebraic Expressions - Definition and Examples

Algebra is a subpart of mathematics that deals with relations, operations, and their constructions. It is one of the building blocks of mathematics, and it finds a huge variety of applications in our day-to-day life.

Algebra is one of the many various branches of Mathematics. It deals with the binary relations, operations and constructions of various mathematical functions. Algebra is an integral part of a student’s education. It helps in developing the overall understanding of other Math branches. The other branches of Math include Calculus, Arithmetic, and Geometry etc.

The word Algebra is taken from the Arabic phrase al-jebr which means "reunion of broken parts". It is the study of multiple operations and relations, various constructions of geometric figures and the explanation and proofs of concepts such as polynomials, equations, and algebraic structures.

Now, the question arises, how is Algebra different from the other branches in Math? The answer to this is the Algebraic Expressions used in Algebra.

To know further, read on.

### What is an Algebraic Expression?

The expression of numbers using alphabets or letters with their actual values unknown are known as algebraic expressions. An algebraic expression is one or more algebraic terms used to express a concept. The basic building blocks of an Algebraic expression are variables and constants and operating symbols such as plus, minus signs.

3x^{2} + 2y + 7xy + 5

Algebraic expressions are just a set of variables and constants that are separated by plus or minus signs.

In this article, we will mainly focus on the definition and properties of constants and variables.

Algebraic expressions can be monomial, binomial and polynomial. Given below are the definitions of the three types.

### Monomial Expression

Algebraic Expressions having one term is known as a monomial.

7xy is an example of a monomial Expression.

### Binomial Expression

Algebraic Expressions are usually having w=two terms are called binomial.

4x+6 is an example of a binomial expression.

### Polynomial Expression

This expression generally contains more than two terms with non-negative integral components of variables is known as a Polynomial.

ax+3y+6c=0 is an example of a polynomial expression.

There are two types of Expressions; they are Numeric Expressions and Variable Expressions.

Numeric Expression consists of numbers; never include variables.

For example,

10-2, 3*4 etc.

Variable Expressions contain both variables and numbers to define a particular expression.

For example,

5x+y, 5ac-44 etc.

### What are Constants?

Constants are that part of the algebraic expression that involve only numbers. We call them constants because the value is always the same. It is definite. There are no variables in the term that can change the value of the constant. The number 8 is a constant, because it has a particular value, and it is known to everyone. It can’t be changed. In the expression 3XY – 4 = 2Y, the second term 4 is the constant. 3XY cannot be a constant because the values X and Y can be varied, and hence will vary the entire term 3XY.

Constants are the symbols that have fixed numerical values such as 2,8,-5,-7,12, etc.

### What are Variables?

In an algebraic expression, the letters represent variables. They are not constant; the value of these terms can be changed from time to time. In the expression 2y+3x=0, the values x and y represent variables. Y can be 2,3, or any number and x can also be any number that satisfies the equation. More than one value can be substituted for the letters in an algebraic expression.

Variables are quantities whose values are unknown which means they have no numerical values and are represented by an alphabet such as a,b,c,d, etc.

Constants and variables are a part of algebraic expressions and are considered the basic building blocks of algebraic expressions. For example-

For an algebraic expression

2x+3

3 is a constant since it has a fixed value

x is a variable, while 2 is the coefficient of x

### Some more Examples of Variables and Constants

In 4a, a is variable and 4 is a constant.

In -5pq, p and q are variables and -5 is a constant.

In 8y, y is a variable and 8 is a constant but 8y together is a variable.

The product of variables and constants is always a variable.

### Difference between Variables and Constants

### The Entire Article in a Nutshell

Consider the type statement ‘4x+2y=12.’

What does ‘x’ and ‘y’ represent? They are quantities that can be continuously varied and can be substituted with different values. Hence, it is called a variable. It is usually an English alphabet that represents these values. A variable is a letter that signifies an unidentified. It always serves a number, but it carries varying values when written in the expression. In this expression x and y are variables. All algebraic expressions and terms consist of a minimum of one variable. It is this variable that distinguishes an algebraic expression from an arithmetic one. The variable in a mathematical expression can explain infinite possibilities to determine the value of the expression.

The constants over here are 4, 2 and 12. These values cannot be changed and represent a fixed mathematical expression at all times. Under no circumstances can the values be assumed differently or written differently.

#### Example 1. Substitute the variables and constants from the following expressions.

#### 2

3y+5

ax^{2}+bx+c^{2}

\[\sqrt{2}\] +x^{a}

\[\frac{1}{\sqrt{2+x}}\]

Ans:

#### Example 2. State whether the following statements are true or false.

#### 10 is a constant, z is a variable but 10z is a variable.

#### 2 is a constant, p is a variable but 2+p is a variable.

#### 12 is a constant, m is a variable but 12+m is a constant.

#### 0 is a constant.

Ans:

True

True

False

True

### Formulas used in Algebraic Equations

(a+b)

^{2}=a^{2}+2ab+b^{2}

(a-b)

^{2}=a^{2}-2ab+b^{2}

a

^{2}-b^{2}=(a+b)(a-b)

(a+b)

^{3}=a^{3}+b^{3}+3ab(a+b)

(a-b)

^{3}=a^{3}-b^{3}-3ab(a-b)

a

^{3}+b^{3}=(a+b)(a^{2}-ab+b^{2})

a

^{3}-b^{3}=(a-b)(a^{2}+ab+b^{2})

## FAQs on Variables and Constants in Algebraic Expressions

**1. What are the different types of algebraic expressions?**

Algebraic expressions can be termed into three different types which are-

Monomial- The expressions in algebra that have only one term are known as monomial expressions. They can either be a constant, a variable or a combination of both. For example- 8, 4x, 6ab, etc.

Binomial- The expressions in algebra that have two terms are known as binomial expressions. It can be a sum or difference between two monomials. For example- 4+2a, 2y+4x, etc.

Polynomial- The expressions in algebra with more than two terms are known as polynomial expressions. For example- x

^{2}+2a+y^{3}

**2. Why are variables and constants important?**

Variables and constants play a very important role in mathematics as well as other subjects. To progress in Maths, the students must know how to read and write variables and constants in maths. Algebra is considered to be the language of maths, therefore without knowing the importance and use of algebra students cannot solve the mathematical problems at higher standards. At the same time, variables and constants are an important part of computation also. To know more about algebraic expressions, students can visit Vedatu’s study material on variables and constants.

**3. What are terms, like terms and unlike terms in algebra?**

A term is defined as a signed variable, constant or a combination of both. For example, in the expression 4x+2y, 4x and 2y are two different terms that are separated by a mathematical operation. Terms are of two types- like and unlike.

Similar terms in an expression which means they have the same variables and powers are known as like terms. Like terms can be added, subtracted and multiplied. For example, x^{2}2 and 2x^{2} are like terms.

Terms that are not like terms are known as, unlike terms. For example 4xy and 4ay.

**4. Solve the expression 16x ^{2}-4x^{2} using the standard identity formula.**

Given 16x^{2}+4x^{2} which can be written as (4x)^{2}-(2x)^{2}

Using the identity-

a^{2}-b^{2}=(a+b)(a-b)

(4x)^{2}-(2x)^{2}=(4x+2x)(4x-2x)

(4x)^{2}-(2x)^{2}=(6x)(2x)

(4x)^{2}-(2x)^{2}=12x^{2}

(4x)^{2}-(2x)^{2}=12x^{2}

**5. Why are standard identities important in algebra?**

In algebra, there are a total of 8 types of standard identities that help while solving mathematical problems and equations. Standard identities are identities that hold the value of each one of its variables. Using standard identities helps the students to solve the equations quickly and makes the calculations easier in primary as well as higher classes. Therefore, it is very important to learn all the standard identities so that the students can easily manipulate the algebra.