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BITSAT2011MathematicsMatricesActual

If (A= [ array lll 2 & 0 & 0 2 & 2 & 0 2 & 2 & 2 array ] ), then ( adj ( adj A) ) is equal to -

Options

  1. A(8 [ array lll 1 & 0 & 0 1 & 1 & 0 1 & 1 & 1 array ] )
  2. B(16 [ array lll 1 & 0 & 0 1 & 1 & 0 1 & 1 & 1 array ] )
  3. C(64 [ array lll 1 & 0 & 0 1 & 1 & 0 1 & 1 & 1 array ] )
  4. DNone of these

Correct answer

B. (16 [ array lll 1 & 0 & 0 1 & 1 & 0 1 & 1 & 1 array ] )

Step-by-step solution

(|A|= [ array lll 2 & 0 & 0 2 & 2 & 0 2 & 2 & 2 array ]=(2)(2)(2)=8 ) Now adj (( adj A)=| A |³⁻² ~A ) (=8 [ array lll 2 & 0 & 0 2 & 2 & 0 2 & 2 & 2 array ]=16 [ array ccc 1 & 0 & 0 1 & 1 & 0 1 & 1 & 1 array ] )

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