NCERT Solutions for Class 11 Maths Chapter 7- Permutations and Combinations Exercise 7.2

NCERT Solutions have been carefully compiled and developed as per the latest CBSE syllabus. The NCERT Solutions contain detailed step-by-step explanation of all the problems that are present in the NCERT textbook. The Exercise 7.2 of NCERT Solutions for Class 11 Maths Chapter 7- Permutations and Combinations is based on the following topics:

  1. Permutations
    1. Permutations when all the objects are distinct
    2. Factorial notation

The NCERT Solutions for Class 11 Maths enhance topics with frequent, focused, engaging math challenges and activities that strengthen math concepts. Each question of the exercise has been carefully solved for the students to understand, keeping the examination point of view in mind.

Download PDF of NCERT Solutions for Class 11 Maths Chapter 7- Permutations and Combinations Exercise 7.2

ncert solution class 11 chapter 7 permutations and combinations ex 2 1
ncert solution class 11 chapter 7 permutations and combinations ex 2 2
ncert solution class 11 chapter 7 permutations and combinations ex 2 3

 

Solutions for Class 11 Maths Chapter 7 – Exercise 7.2

1. Evaluate
(i) 8!

(ii) 4! – 3!

Solution:

(i) Consider 8!

We know that 8! = 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1

= 40320

(ii) Consider 4!-3!

4!-3! = (4 × 3!) – 3!

Above equation can be written as

= 3! (4-1)

= 3 × 2 × 1 × 3

= 18

2. Is 3! + 4! = 7!?

Solution:

Consider LHS 3! + 4!

Computing left hand side, we get

3! + 4! = (3 × 2 × 1) + (4 × 3 × 2 × 1)

= 6 + 24

= 30

Again consider RHS and computing we get

7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5040

Therefore LHS ≠ RHS

Therefore 3! + 4! ≠ 7!

3. Compute 

NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 1

Solution:

 NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 2

4. If NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 3find x.

Solution:

NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 4

5. Evaluate

 NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 5,

When
(i) n = 6, r = 2
(ii) n = 9, r = 5

Solution:

NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 6


Access other exercise solutions of Class 11 Maths Chapter 7- Permutations and Combinations

Exercise 7.1 Solutions 6 Questions

Exercise 7.3 Solutions 11 Questions

Exercise 7.4 Solutions 9 Questions

Miscellaneous Exercise On Chapter 7 Solutions 11 Questions

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