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

NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Ex 7.2 are part of NCERT Solutions for Class 11 Maths. Here we have given NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Ex 7.2.

• Permutations and Combinations Class 11 Ex 7.1
• Permutations and Combinations Class 11 Ex 7.3
• Permutations and Combinations Class 11 Ex 7.4

Board	CBSE
Textbook	NCERT
Class	Class 11
Subject	Maths
Chapter	Chapter 7
Chapter Name	Permutations and Combinations
Exercise	Ex 7.2
Number of Questions Solved	5
Category	NCERT Solutions

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

Question 1.
Evaluate
(i) 8!
(ii) 4!-3!
Solution.
(i) 8! = 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 = 40320
(ii) 4! – 3! = (1 x 2 x 3 x 4) – (1 x 2 x 3) = 24 – 6 = 18

Question 2.
Is 3! + 4! = 7! ?
Solution.
3! + 4! = (1 x 2 x 3) + (1 x 2 x 3 x 4) = 6 + 24 = 30 … (i)
7! = 1 x 2 x 3 x 4 x 5 x 6 x 7 = 5040 ………(ii)
From (i) & (ii), we get 3! + 4! ≠ 7!.

Question 3.

Solution.

Question 4.
, findx.
Solution.
We have,

Question 5.
Evaluate , when
(i) n = 6, r = 2
(ii) n = 9, r = 5
Solution.
(i)

(ii)

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