1. Class 12
  2. Sample Papers, Previous Year Papers and Other Questions
  3. CBSE Class 12 Sample Paper for 2019 Boards

Question 1 - CBSE Class 12 Sample Paper for 2019 Boards

Last updated at Dec. 12, 2018 by

Question 1

If A and B are invertible matrices of order 3, |A| = 2, |(AB) -1 | = – 1/6. Find |B|

Slide1.JPG

Slide2.JPG

  1. Class 12
  2. Sample Papers, Previous Year Papers and Other Questions

    3. CBSE Class 12 Sample Paper for 2019 Boards

    CBSE Class 12 Sample Paper for 2018 Boards →

Transcript

Question 1 If A and B are invertible matrices of order 3, |๐ด| = 2, |(๐ด๐ต)^(โˆ’1) | = โ€“ 1/6 . Find |๐ต| Theory We know that A A-1 = I So, |A A-1| = |I| |A A-1| = 1 |A| |A-1| = 1 |A-1| = 1/|๐ด| Just for reference, no need to write Given |๐ด| = 2, |(๐ด๐ต)^(โˆ’1) | = โ€“ 1/6 We know that |(๐ด๐ต)^(โˆ’1) | = 1/(|๐ด๐ต|) |(๐ด๐ต)^(โˆ’1) | = 1/|๐ด||๐ต| โˆ’1/6 = 1/(2 ร— |๐ต| ) 2 ร— |๐ต| = โ€“6 |๐ต| = (โˆ’6)/2 |๐‘ฉ| = โ€“ 3

Class 12
Sample Papers, Previous Year Papers and Other Questions

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.