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MHT CET20226 Aug 2022Evening ShiftMathematicsMatricesActual

Given A = [ array lll x & 3 & 2 1 & y & 4 2 & 2 & z array ], x y z=60 and 8 x+4 y+3 z=20 , then A ( adjA ) is equal to

Options

  1. A[ array ccc 60 & 0 & 0 0 & 60 & 0 0 & 0 & 60 array ]
  2. B[ array ccc 20 & 0 & 0 0 & 20 & 0 0 & 0 & 20 array ]
  3. C[ array ccc 68 & 0 & 0 0 & 68 & 0 0 & 0 & 68 array ]
  4. D[ array ccc 108 & 0 & 0 0 & 108 & 0 0 & 0 & 108 array ]

Correct answer

C. [ array ccc 68 & 0 & 0 0 & 68 & 0 0 & 0 & 68 array ]

Step-by-step solution

aligned & |A|=x(y z-8)+3(8-z)+2(2-2 y) & =x y z-8 x+24-3 z+4-4 y & =x y z-(8 x+4 y+3 z)+28 & =60-20+28 & =68 aligned we have, A adj (A)=|A| I= [ array ccc 68 & 0 & 0 0 & 68 & 0 0 & 0 & 68 array ]

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