CBSE Class 11 Mathematics Chapter 6: Linear Inequalities - NCERT Solutions

NCERT Solutions PDF Class 11 PDF

This chapter provides NCERT Solutions for Class 11 Mathematics, focusing on Linear Inequalities (Chapter 6). Students will learn to solve linear inequalities in one variable for different sets of numbers, including natural numbers, integers, and real numbers. The solutions cover various types of inequalities, demonstrating how to isolate the variable and determine the solution set. Key concepts include understanding the properties of inequalities, such as reversing the inequality sign when multiplying or dividing by a negative number. These detailed solutions are designed to help students grasp the concepts thoroughly and prepare effectively for their examinations by offering step-by-step guidance and clear explanations for each problem.

Quick info

BoardCBSE
ClassClass 11
SubjectMathematics
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 6

Chapter summary

Chapter 6, Linear Inequalities, for Class 11 Mathematics NCERT Solutions focuses on solving inequalities involving one variable. The exercises cover finding solutions for natural numbers, integers, and real numbers. Students will practice manipulating inequalities to find the solution set, understanding the implications of different number sets on the final answer. This chapter builds a foundational understanding of inequalities, crucial for more advanced mathematical concepts.

Learning outcomes

  • Understand the concept of linear inequalities in one variable.
  • Solve linear inequalities for natural numbers.
  • Solve linear inequalities for integers.
  • Solve linear inequalities for real numbers.
  • Apply the rules of inequality manipulation correctly.
  • Represent solution sets on the number line.

Topics covered

Paper topics

  • Linear Inequalities in One Variable
  • Solving Inequalities for Natural Numbers
  • Solving Inequalities for Integers
  • Solving Inequalities for Real Numbers
  • Properties of Inequalities
  • Algebraic Manipulation of Inequalities

Important topics

  • Solving inequalities for different number sets
  • Handling negative multipliers/divisors
  • Representing solution sets
  • Basic algebraic manipulation of inequalities

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Questions and Solutions

Question 1

Solve the inequality 24x < 100, when: (i) x is a natural number (ii) x is an integer
Solution:

The given inequality is 24x < 100.

To solve for x, we divide both sides by 24:

\frac{24x}{24} < \frac{100}{24}

This simplifies to:

x < \frac{25}{6}

Note that \frac{25}{6} is approximately 4.17.

(i) When x is a natural number:

We need to find the natural numbers that are less than \frac{25}{6}. The natural numbers are 1, 2, 3, 4, ...

The natural numbers less than 4.17 are 1, 2, 3, and 4.

Thus, the solution set when x is a natural number is \{1, 2, 3, 4\}.

(ii) When x is an integer:

We need to find the integers that are less than \frac{25}{6} (approximately 4.17).

The integers less than 4.17 include ..., -3, -2, -1, 0, 1, 2, 3, 4.

Thus, the solution set when x is an integer is \{..., -3, -2, -1, 0, 1, 2, 3, 4\}.

Question 2

Solve the inequality -12x > 30, when: (i) x is a natural number (ii) x is an integer
Solution:

The given inequality is -12x > 30.

To solve for x, we divide both sides by -12. Remember to reverse the inequality sign when dividing by a negative number:

\frac{-12x}{-12} < \frac{30}{-12}

This simplifies to:

x < -\frac{5}{2}

Note that -\frac{5}{2} is -2.5.

(i) When x is a natural number:

Natural numbers are positive integers (1, 2, 3, ...). There are no natural numbers that are less than -2.5.

Thus, there is no solution when x is a natural number.

(ii) When x is an integer:

We need to find the integers that are less than -2.5.

The integers less than -2.5 are ..., -5, -4, -3.

Thus, the solution set when x is an integer is \{..., -5, -4, -3\}.

Question 3

Solve the inequality 5x - 3 < 7, when: (i) x is an integer (ii) x is a real number
Solution:

The given inequality is 5x - 3 < 7.

First, add 3 to both sides of the inequality:

5x - 3 + 3 < 7 + 3

This simplifies to:

5x < 10

Now, divide both sides by 5:

\frac{5x}{5} < \frac{10}{5}

This gives us:

x < 2

(i) When x is an integer:

We need to find the integers that are less than 2.

The integers less than 2 are ..., -4, -3, -2, -1, 0, 1.

Thus, the solution set when x is an integer is \{..., -4, -3, -2, -1, 0, 1\}.

(ii) When x is a real number:

The solution is all real numbers x such that x is less than 2.

This can be represented in interval notation as (-\infty, 2).

Thus, the solution set when x is a real number is x \in (-\infty, 2).

Question 4

Solve the inequality 3x + 8 > 2, when: (i) x is an integer (ii) x is a real number
Solution:

The given inequality is 3x + 8 > 2.

First, subtract 8 from both sides of the inequality:

3x + 8 - 8 > 2 - 8

This simplifies to:

3x > -6

Now, divide both sides by 3:

\frac{3x}{3} > \frac{-6}{3}

This gives us:

x > -2

(i) When x is an integer:

We need to find the integers that are greater than -2.

The integers greater than -2 are -1, 0, 1, 2, 3, ...

Thus, the solution set when x is an integer is \{-1, 0, 1, 2, 3, ...\}.

(ii) When x is a real number:

The solution is all real numbers x such that x is greater than -2.

This can be represented in interval notation as (-2, \infty).

Thus, the solution set when x is a real number is x \in (-2, \infty).

Common mistakes

  • Forgetting to reverse the inequality sign when multiplying or dividing by a negative number.
  • Incorrectly identifying natural numbers or integers within a given range.
  • Confusing the representation of solution sets for integers and real numbers.
  • Errors in basic arithmetic operations while solving inequalities.

Revision tips

  • Review the properties of inequalities, especially when dealing with negative numbers.
  • Practice solving inequalities for different number sets (natural, integer, real) to understand the distinctions.
  • Pay close attention to the inequality sign (<, >, ≤, ≥) and its implications for the solution set.
  • Visualize the solution set on a number line for real number solutions.

Practice MCQs

Q1. What is the solution set for 24x < 100 when x is a natural number?

Q2. If -12x > 30, what is the solution set for x as an integer?

Q3. For the inequality 5x - 3 < 7, what is the solution set when x is a real number?

Q4. What is the solution set for 3x + 8 > 2 when x is an integer?

Frequently asked questions

What is the main focus of Chapter 6, Linear Inequalities, for Class 11 Maths?

Chapter 6 focuses on solving linear inequalities in one variable for different sets of numbers like natural numbers, integers, and real numbers, and understanding the properties of inequalities.

How do the solutions handle inequalities involving negative numbers?

The solutions demonstrate that when multiplying or dividing an inequality by a negative number, the direction of the inequality sign must be reversed.

What is the difference between solving for integers and real numbers?

For integers, the solution set consists of discrete whole numbers within the range. For real numbers, the solution set is a continuous interval on the number line.

Are the questions in these NCERT Solutions similar to exam questions?

Yes, these NCERT Solutions cover the fundamental concepts and problem types typically found in Class 11 Mathematics exams related to linear inequalities.

How can these solutions help in exam revision?

They provide clear, step-by-step explanations and cover various scenarios, helping students reinforce their understanding and practice problem-solving techniques for linear inequalities.

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