Ex 3.2

Chapter 3 Class 12 Matrices
Serial order wise

### Transcript

Ex 3.2, 22 (Introduction) Assume X, Y, Z, W and P are matrices of order 2 × n, 3 × k, 2 × p, n × 3 , and p × k respectively. If n = p, then the order of the matrix 7X – 5Z is (A)p × 2 (B) 2 × n (C) n × 3 (D) p × n X =[■8(1&0@2&3)]_(2 × 2) 7X =[■8(7&0@14&21)]_(2 × 2) 7X – 5Z =[■8(𝟕&𝟎@𝟏𝟒&𝟐𝟏)]_(𝟐 × 𝟐)– [■8(𝟎&𝟏𝟎@𝟏𝟓&𝟓)]_(𝟐 × 𝟐)=[■8(𝟕&−𝟏𝟎@−𝟏&𝟏𝟔)]_(𝟐 × 𝟐) Therefore, ∴ Order of X = Order of 7X & Order of Z = Order of 5Z And, Order of 7X – 5Z = Order of 7X = Order of 5Z Ex 3.2, 22 Assume X, Y, Z, W and P are matrices of order 2 × n, 3 × k, 2 × p, n × 3 , and p × k respectively. If n = p, then the order of the matrix 7X – 5Z is (A)p × 2 (B) 2 × n (C) n × 3 (D) p × n Order of matrix X = 2 × n Order of matrix 7X = 2 × n Order of matrix Z = 2 × p Order of matrix 5Z = 2 × p ∴ Order of matrix 5Z = 2 × n ∴ Order of 7X – 5Z = Order of 7X = Order of 5Z = 2 × n. Hence, Correct answer is B

#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.