Class 8 Maths: Algebraic Expressions Explained with Easy Examples

Ever come across a math problem such as 3x + 5 or 2a - 4b and asked yourself what the letters mean? These are known as algebraic expressions and are one of the most important topics of the Class 8 maths book. After you grasp how they work, they are very easy to solve and even fun. 

In this blog, we will explain algebraic expressions class 8 in easy language with simple examples, tables and practice questions. From CBSE Class 8 maths book study to additional support, this guide has got you covered.

What Is an Algebraic Expression?

An algebraic expression is a math statement that has numbers, letters (called variables), and operations like addition, subtraction, multiplication, or division. 

For example: 3x + 5 is an algebraic expression. Here, 3 is the coefficient, x is the variable, and 5 is the constant. 

Imagine it. Suppose that you have some pencils, but you don't know how many. You write it as x. If your friend gives you 3 more boxes with x pencils in each, then you will have 3x pencils. If you already had 5 loose pencils, the total would be 3x + 5. This is an algebraic expression in the real world.

Key Terms You Must Know

It is important to know the basic words used in this chapter of CBSE Class 8 Maths book before solving problems.

Types of Algebraic Expressions

Algebraic expressions are grouped according to the number of terms in them. These types are clearly explained in the class 8 maths book in the chapter on algebraic expressions.

A term is one of the components of an expression. The + and - are used to separate terms. For example, in 4x + 3y - 2, there are three terms: 4x, 3y, and -2.

Addition of Algebraic Expressions

Adding algebraic expressions is just as simple as adding like terms together. Terms with the same variable and the same power are alike terms.

Example: Add 3x + 2y and 5x + 4y.

Step 1: Combine like terms. (3x + 5x) + (2y + 4y)

Step 2: Add them.  8x + 6y

That is the answer. The only rule is that you can add and subtract terms with the same variable. x and y are different variables so 3x and 4y cannot be added together.

Subtraction of Algebraic Expressions

Subtraction is similar. Like terms are subtracted from each other.

Example: Subtract (2a + b) from (7a + 3b).

Step 1: Write it as (7a + 3b) - (2a + b)

Step 2: Open the brackets.        7a + 3b - 2a - b

Step 3: Combine like terms.  (7a - 2a) + (3b - b)

Step 4: Simplify.                 5a + 2b

Be sure to open brackets with a minus sign. All the signs within the brackets are changed.

Multiplication of Algebraic Expressions

To multiply two algebraic expressions, multiply the coefficients and add the exponents of the like variables.

Example 1: Multiply 3x and 4y.

Answer: 3 × 4 × x × y = 12xy

Example 2: Multiply 2x and 3x.

Answer: 2 × 3 × x × x = 6x²

It is an important concept of the algebraic expressions class 8 and is asked regularly in exams and the class 8 question bank.

Finding the Value of an Expression

In some cases, the question will provide you the value of the variable and ask you for the answer. This is known as substitution.

Example: Find the value of 2x + 3 when x = 5.

Step 1: Replace x with 5.         2(5) + 3

Step 2: Multiply.                 10 + 3

Step 3: Add.                      13

So the value of the expression is 13. This kind of questions is frequently asked in class 8 maths practice.

Maths Practice for Class 8 - Try These Questions

This is a small question bank for class 8th algebraic expressions to practice. Attempt to solve them independently first and then verify the answers.

Solving these questions on a daily basis will help you to score well in maths practice for class 8.

Tips to Score Well in Algebraic Expressions

Be careful when reading each term and determine the variable and coefficient before solving. When adding and subtracting, always group like terms together. Remember to change all the signs within the brackets when subtracting. Solve the CBSE Class 8 Maths book at least 5 questions a day to gain confidence. Update the definitions of terms such as monomial, binomial, and coefficient as needed.

Conclusion

Algebraic expressions class 8 can be confusing at first glance but once you know the basic terminology and rules, it is very easy. Be aware of like terms, watch out for signs when subtracting and practice regularly with the practice questions in your CBSE Class 8 maths book. 

Keep revising with the practice table in this blog as your mini class 8 question bank. By practicing maths regularly for class 8, you will be able to solve algebraic expression problems easily and confidently in your exam.

Explore Oswaal’s Class 8 collection today to support better understanding, regular practice, and confident exam preparation.