Question

A. square matrix $A$ of order $3,$ has $|A|=5,$ find $|A$ adja|

Answer 1

Given $A$ is a matrix of order $3$

$⟹|A|=5$

$⟹|adjA|=|A{|}^{(3-1)}=|A{|}^2=5^2=25$

$|AadjA|=|A|\times |adjA|=5\times 25=125$