A) \[{{81}^{2}}\]
B) \[81\]
C) \[729\]
D) \[27\]
Correct Answer: B
Solution :
Given, det \[(A)=3\] and \[n=3\] (order of A) Now, adj \[(adj\,A)=|A{{|}^{n-2}}A\] \[={{(3)}^{3-2}}\,A\] \[=3\,A\] \[adj\,\,\{adj\,\,(adjA)\}=adj\,\,(3A)\] \[={{3}^{n-1}}\,adj\,A\] \[=9\,adj\,A\] \[|adj\,\{adj\,\,(adjA)\}\,=|9\,adj\,A|\] \[=9|adj\,A|\] \[=9|A{{|}^{n-1}}\] \[=9{{(3)}^{3-1}}\] \[=9\times 9=81\]
You need to login to perform this action.
You will be redirected in
3 sec
