NCERT 12 Maths Matrices Chapter 3 – Exercise 3.4

ncert 12 maths chapter 3 ex 3.4 ques 1
ncert 12 maths chapter 3 ex 3.4 ans 1
ncert 12 maths chapter 3 ex 3.4 ques 2
ncert 12 maths chapter 3 ex 3.4 ans 2
ncert 12 maths chapter 3 ex 3.4 ques 3
ncert 12 maths chapter 3 ex 3.4 ans 3
ncert 12 maths chapter 3 ex 3.4 ques 4
ncert 12 maths chapter 3 ex 3.4 ans 4
ncert 12 maths chapter 3 ex 3.4 ques 5
ncert 12 maths chapter 3 ex 3.4 ans 5
ncert 12 maths chapter 3 ex 3.4 ques 6
ncert 12 maths chapter 3 ex 3.4 ans 6
ncert 12 maths chapter 3 ex 3.4 ques 7
ncert 12 maths chapter 3 ex 3.4 ans 7
ncert 12 maths chapter 3 ex 3.4 ques 8
ncert 12 maths chapter 3 ex 3.4 ans 8
ncert 12 maths chapter 3 ex 3.4 ques 9
ncert 12 maths chapter 3 ex 3.4 ans 9
ncert 12 maths chapter 3 ex 3.4 ques 10
ncert 12 maths chapter 3 ex 3.4 ans 10
ncert 12 maths chapter 3 ex 3.4 ques 11
ncert 12 maths chapter 3 ex 3.4 ans 11
ncert 12 maths chapter 3 ex 3.4 ques 12

Now, in the above equation, we can see all the elements are zero in the second row of the matrix on the LHS. Therefore, A-1 does not exist.
Note: Suppose A = IA, after applying the elementary transformation, if any row or column of a matrix on LHS is zero, then A-1 does not exist.

ncert 12 maths chapter 3 ex 3.4 ques 13
ncert 12 maths chapter 3 ex 3.4 ans 13
ncert 12 maths chapter 3 ex 3.4 ques 14

Now, in the above equation, we can see all the elements are zero in the second row of the matrix on the LHS. Therefore, A-1 does not exist.

ncert 12 maths chapter 3 ex 3.4 ques 15
ncert 12 maths chapter 3 ex 3.4 ans 15
ncert 12 maths chapter 3 ex 3.4 ans 15.1
ncert 12 maths chapter 3 ex 3.4 ques 16
ncert 12 maths chapter 3 ex 3.4 ans 16
ncert 12 maths chapter 3 ex 3.4 ans 16.1
ncert 12 maths chapter 3 ex 3.4 ques 17
ncert 12 maths chapter 3 ex 3.4 ans 17
ncert 12 maths chapter 3 ex 3.4 ans 17.1

Direction (Q. No. 18) Choose the correct answer in the following question.
1. Matrices A and B will be inverse of each other only if
(a) AB = BA
(b) AB = BA = O
(c) AB = 0, BA = I
(d) AB = BA = I
Sol. We know that if A is a square matrix of order m and if there exists another square matrix B of the same order m, such that AB = BA = I, then B is said to be the inverse of A. In this case, it is clear that A is the inverse of B. Thus, matrices A and B will be inverse of each other only if AB = BA = I. So, correct option is (d)
Updated: October 19, 2020 — 2:36 pm

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