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Using Cofactors of elements of second row, evaluate `Delta=|(5, 3, 8),( 2, 0, 1),( 1, 2 ,3)|`

Answer» Here, `A = |[5,3,8],[2,0,1],[1,2,3]|`
First we will find minor of second row.
`M_21 = 9-16 = -7`
`M_22 = 15-8 = 7`
`M_23 = 10-3 = 7`
Now, we will find the cofactors using these minors.
`A_21 = (-1)^(2+1)M_21 = -1(-7) = 7`
`A_22 = (-1)^(2+2)M_22 = 1(7) = 7`
`A_23 = (-1)^(2+3)M_23 = -1(7) = -7`
Now, `a_21 = 2`
`a_22 = 0`
`a_23 =1`
`:. Delta = a_21A_21+a_22A_22+a_23A_23`
`=>Delta = 2(7)+0(7)+1(-7) = 14+0-7 = 7`
`:. Delta = 7.`


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