Question

Please answer this question

[CosФ i sin Ф]
If 2A=[i sin Ф cos Ф], find k so that A (adjA)= ki

Answer 1

We know that A−1=adj(A)/det(A)

⇒adj(A)=det(A)A−1                    (2)

 

Putting equation (2) in equation (1),we get

adj(kA)=kn−1adj(A)   which is the desired result.