Linear Equations In One Variable - Exercise-wise Questions and Answers For Class 8 Maths - Free PDF Download
FAQs on NCERT Solutions For Class 8 Maths Chapter 2 Linear Equations In One Variable - 2025-26
1. What is the basic step-by-step method to solve a linear equation in one variable as per NCERT Class 8 Maths Chapter 2?
The correct method for solving a linear equation in one variable involves a few key steps:
- Combine Like Terms: Group all terms with the variable on one side of the equation (usually the Left-Hand Side or LHS) and all constant terms on the other side (RHS).
- Isolate the Variable: Use inverse operations (addition/subtraction or multiplication/division) on both sides of the equation to get the variable by itself.
- Solve for the Variable: Simplify the equation to find the final value of the variable.
The fundamental principle is to always perform the same operation on both sides to keep the equation balanced.
2. How many exercises are in NCERT Class 8 Maths Chapter 2, and what is the main focus of each?
According to the 2025-26 CBSE syllabus, Chapter 2, Linear Equations in One Variable, has two main exercises:
- Exercise 2.1: Focuses on solving basic linear equations where the variable appears on only one side of the equality.
- Exercise 2.2: Contains more complex problems, including equations with variables on both sides and application-based word problems that must first be converted into a linear equation.
3. What is the correct method for solving equations from NCERT Exercise 2.2, where variables are on both sides?
To solve equations with variables on both sides, like 3x - 5 = x + 3, follow the correct CBSE pattern:
- First, bring all variable terms to one side. For example, subtract 'x' from both sides to get 2x - 5 = 3.
- Next, move all constant terms to the opposite side. Add 5 to both sides to get 2x = 8.
- Finally, isolate the variable by dividing both sides by its coefficient. Here, divide by 2 to get x = 4.
4. How do you solve problems in Chapter 2 where the variable appears in the denominator of a fraction?
For equations that are not initially linear, such as those with variables in the denominator, the first step is to reduce them to a linear form. The standard method is cross-multiplication. For an equation like (x + 1) / (2x + 3) = 3 / 8, you multiply the numerator of each side by the denominator of the other. This results in 8(x + 1) = 3(2x + 3), which is a standard linear equation that you can then solve.
5. After finding a solution, how can you verify if your answer to an NCERT problem is correct?
Verifying your answer is a crucial step. To do this, substitute the value you found for the variable back into the original equation. Calculate the value of the Left-Hand Side (LHS) and the Right-Hand Side (RHS) separately. If the LHS equals the RHS, your solution is correct. If they are not equal, you should recheck your calculations.
6. What is the most common mistake to avoid when solving word problems from this chapter?
A frequent error in solving word problems is the incorrect translation of the problem's language into a mathematical equation. For example, incorrectly writing “a number decreased by 10” as 10 - x instead of the correct form x - 10. It is essential to carefully define your variable and accurately represent the relationships between quantities to set up the correct equation.
7. When solving a linear equation, why does moving a term to the other side of the '=' sign change its operation from '+' to '-'?
This is a shortcut known as transposing. It is not a separate mathematical rule but a faster way of applying the balancing principle. When you move a positive term (e.g., +5) to the other side, you are essentially subtracting that term from both sides of the equation to maintain equality. The effect is that it appears on the other side with its sign changed.
8. What is the correct procedure for solving linear equations that involve multiple fractions?
The most efficient method is to eliminate the fractions first. To do this, find the Least Common Multiple (LCM) of all the denominators in the equation. Then, multiply every term on both sides of the equation by this LCM. This process, known as 'clearing the denominators', transforms the fractional equation into a simpler one with integers, which is much easier to solve accurately.
9. How does the solution method differ for an 'equation' versus an 'expression' in this chapter?
An expression (e.g., 5x + 10) can only be simplified by combining like terms; you cannot 'solve' it because it doesn't have an equals sign. An equation (e.g., 5x + 10 = 30) has an equals sign, which allows you to find a specific value for the variable that makes the statement true. The NCERT solutions for this chapter focus on the methods for solving equations, not just simplifying expressions.
10. Why is it important to use brackets when multiplying a binomial in an equation, like in 2(x+3)?
Using brackets is essential for applying the distributive property correctly. In an expression like 2(x + 3), the number outside the bracket must multiply every term inside it. A common error is to only multiply the first term (getting 2x + 3). The correct method is 2*x + 2*3, which simplifies to 2x + 6. Failing to do this will lead to an incorrect solution.











