MCQ
If $A = \left[ {\begin{array}{*{20}{c}}4&2\\3&4\end{array}} \right]$,then $|adj\,\,A|$is equal to
  • A
    $16$
  • $10$
  • C
    $6$
  • D
    None of these

Answer

Correct option: B.
$10$
b
(b)  $A = \left[ {\begin{array}{*{20}{c}}4&{  2}\\{  3}&4\end{array}} \right]$

adj $A = \left[ {\begin{array}{*{20}{c}}4&{ - 2}\\{ - 3}&4\end{array}} \right]$

$|adj\,A|\, = (4 \times 4) - ( - 3 \times - 2) = 16 - 6$

$|adj\,A|\,\, = 10.$

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