Q.

Let A be a matrix of order 3×3 and |A| = 5. If |2 adj(3A adj(2A))|=2α·3β·5γ, α,β,γN, then α+β+γ is equal to          [2025]

1 28  
2 25  
3 27  
4 26  

Ans.

(3)

We have, |2 adj(3A adj(2A))|

=23·|3A adj(2A)|2          [ |adj A|=|A|n1, when n is order of matrix A]

=23·(33)2·|A|2·|adj(2A)|2

=23·36·|A|2·(|2A|2)2

=23·36·|A|2[(2)6·|A|2]2

=23·36·|A|2·212·|A|4=215·36·|A|6

=215·36·56=2α·3β·5γ          [ |A| = 5]

By comparing, we get

α=15, β=6, γ=6

  α+β+γ=27.