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The cofactor of the element 4 in the determinant | array lll 1 & 2 & 3 4 & 5 & 6 5 & 8 & 9 array | is

Options

  1. A2
  2. B4
  3. C6
  4. D–6

Correct answer

C. 6

Step-by-step solution

The co-factor of an element a_ i j of det A is equal to (-1)^ i+j times its minor. Co-factor aligned C _ i j & =(-1)^ i+j M _ i j C ₂₁ & =(-1)²⁺¹ | array ll 2 & 3 8 & 9 array | & =-1(18-24)=6 aligned

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