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If A=[2−3560415−7]A = \begin{bmatrix} 2 & -3 & 5 \\ 6 & 0 & 4 \\ 1 & 5 & -7 \end{bmatrix}, then which of the following statements are TRUE?

[where AijA_{ij} is the cofactor of the (i, j)th element, aija_{ij} of matrix A, 1>i,j≤31 \gt i, j \le 3.]

(A) a11A31=−24a_{11}A_{31} = -24

(B) a12A32=−66a_{12}A_{32} = -66

(C) a13A33=−90a_{13}A_{33} = -90

(D) a21A21=−24a_{21}A_{21} = -24

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 4

A31=−12A_{31} = -12, so a11A31=2(−12)=−24a_{11}A_{31} = 2(-12) = -24: (A) true. A32=22A_{32} = 22, so a12A32=−3(22)=−66a_{12}A_{32} = -3(22) = -66: (B) true. A33=18A_{33} = 18 gives 5(18)=905(18) = 90, not −90-90. A21=4A_{21} = 4 gives 6(4)=246(4) = 24, not −24-24.

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