Ex 4.4, 3 - Using Cofactors of elements of second row, evaluate - Finding Minors and cofactors

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  1. Chapter 4 Class 12 Determinants
  2. Serial order wise
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Ex 4.4, 3 Using Cofactors of elements of second row, evaluate = 5 3 8 2 0 1 1 2 3 = a21 A21 + a22 A22 + a23 A23 a21 = 2, a21 = 0, a21 = 1, Calculating cofactor of second row i.e. A21 , A22 , And A23 M21 = 5 3 8 2 0 1 1 2 3 = 3 8 2 3 = 3 3 2 8 = 9 16 = 7 M22 = 5 3 8 2 0 1 1 2 3 = 5 8 1 3 = 5 3 8 1= 15 8 = 7 M23 = 5 3 8 2 0 1 1 2 3 = 5 3 1 2 = 5 2 1 3 = 10 3 = 7 Cofactor of a21 = A21 = ( 1)2+1 M21 = ( 1)3 7 = 1 7 = 7 Cofactor of a22 = A22 = ( 1)2+2 M22 = ( 1)4 . 7 = 7 Cofactor of a23 = A23 = ( 1)2 + 3 M31 = ( 1)5 . (7) = ( 1) (7) = 7 Now = a21 A21 + a22 A22 + a23 A23 = 2 7 + 0 7 + 1 ( 7) = 14 + 0 + 7 = 7

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