NCERT Solutions for Class 11 Maths Exercise 7.2 Permutations and Combinations in English and Hindi Medium for session 2022-2023.

## Class 11 Maths Exercise 7.2 Solutions in Hindi and English Medium

Class: 11 | Mathematics |

Chapter: 7 | Exercise: 7.2 |

Topic: | Permutations and Combinations |

Content Type: | Videos and Text Format |

Medium: | Hindi and English medium |

### NCERT Solutions for Class 11 Maths Exercise 7.2

### About Exercise 7.2 of Class 11 Maths

In the second part of the chapter 7 class 11 Mathematics, you will get to study permutation. If you have already paid attention to the first part of the chapter and its example, you already know what permutation is. It is just that you need to know how to explain it which you will study in the definition given here. This states that a permutation is an arrangement in a definite order of several objects taken all at a time.

There will be two types of permutation you will study in 11th Maths NCERT exercise 7.2 of 11th Maths chapter 7. First when the repetition is allowed. For 4 letter word example provide example 1. The required number would be 256. The second one when no repetition allowed. For example, 1 for four-letter words, which state the fourth place can be filled in 1 way, by the multiplication principle, which is 4 x 3 x 2 x 1.

#### Class 11 Maths Exercise 7.2 theorem or Permutation Formula

This is the important part of the chapter 7 of 11th Maths and many questions from exercises 7.2 and above have there used to calculate the solution. The formula here states that if n, r is a positive integer and r is less and equal to n, then the number of permutations of n different objects taken r at a time. If the object does not repeat, the permutation is n (n -1) (n â€“ 2). . . (n â€“ r + 1). The above-given part is from Theorem 1 or the Permutation Formula from NCERT textbook for class 11 Maths. Here permutation of n distinct objects taken r at a time is made by completing r position, in a row with an object chosen from the given n distinct objects.

##### Solving Questions of Class 11 Maths Exercise 7.2

The small introduction of the theorem 1 or permutation formula can be a big part of the examination. This makes it pretty obvious that you must study the proof of the theorem too. This takes us to passage 7.2 factorial notation. The use of factorial mark. Factorial notation is the way of showing the permutation. The sign ! is called here the factorial sign. It is used in solving questions related to permutation and combination. Factorial that is denoted by !, can be expressed as the product of all the natural numbers less than and equal to the number given.

###### Questions of Exercise 7.2 of 11th Maths

To understand it with help of example 5. The factorial of number n is expressed as the product of n and all the natural numbers less than n till 1. This can be shown by writing n! = n, (n -1), (n -2), (n -3)â€¦.. 4, 3, 2, 1. While calculating the factorial you have to keep two important points in mind. Firstly, the factorial of 0 is 1 as per the explanation 7.2. Secondly, the factorial of 1 is always 1.

Though the explanation of factorial is short because the topic is mainly demonstrated. It can be understood in a much better way with the help of explanation or seeing function and its role in a calculation. There are only 5 questions in exercise 7.2 but the questions 4 is important one for exams.