Q18 of 127 Page 122

If A is an invertible matrix of order 2, then det (A^–1) is equal to

{since adj(A) is of order n and |Adj(A)| = |A|^n-1}

Alternative-

We know that AA^-1 = I

So |A||A^-1| = |I| = 1

If Verify that A³ – 6A² + 9A – 4I = O and hence find A^-1.

Let A be a non-singular square matrix of order 3 × 3. Then |adj A| is equal to

Write Minors and Cofactors of the elements of following determinants:

If A is an invertible matrix of order 2, then det (A–1) is equal to