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MHT CET202121 Sep 2021Morning ShiftMathematicsMatricesActual

If A= [ array ccc 1 & 0 & 2 -1 & 1 & -2 0 & 2 & 1 array ] , adj A= [ array ccc 5 & x & -2 1 & 1 & 0 -2 & -2 & y array ] , then value of x + y is

Options

  1. A6
  2. B3
  3. C4
  4. D5

Correct answer

D. 5

Step-by-step solution

x is element a₁₂ in adj (A) x = cofactor of a ₂₁=(-1)²⁺¹ | array ll 0 & 2 2 & 1 array |=-(-4)=4 Similarly, y=(-1)³⁺³ | array cc 1 & 0 -1 & 1 array |=1 x+y=5

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