# if A is an invertible matrix of order 3 and |A|=5, then find |adj.A|.

Toolbox:
• $|adj A|=|A|^{n-1}$
Given:|A|=5 and order n=3.

We know |adj A|=$|A|^{n-1}$

Here n=3.

$|adj A|=|A|^{3-1}$

$\qquad\;=|A|^2$

Therefore $|adj\; A|=5^2$

$\qquad\qquad\qquad=25.$