CBSE Class 12 Sample Paper for 2019 Boards
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CBSE Class 12 Sample Paper for 2019 Boards
Last updated at August 10, 2026 by Teachoo
Question 1
If A and B are invertible matrices of order 3, |A| = 2, |(AB) -1 | = – 1/6. Find |B|
Transcript
Question 1 If A and B are invertible matrices of order 3, |š“| = 2, |(š“šµ)^(ā1) | = ā 1/6 . Find |šµ| Theory We know that A A-1 = I So, |A A-1| = |I| |A A-1| = 1 |A| |A-1| = 1 |A-1| = 1/|š“| Just for reference, no need to write Given |š“| = 2, |(š“šµ)^(ā1) | = ā 1/6 We know that |(š“šµ)^(ā1) | = 1/(|š“šµ|) |(š“šµ)^(ā1) | = 1/|š“||šµ| ā1/6 = 1/(2 Ć |šµ| ) 2 Ć |šµ| = ā6 |šµ| = (ā6)/2 |š©| = ā 3
