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If matrix A=[1279632518]A = \begin{bmatrix}12 & 7 & 9\\6 & 3 & 2\\5 & 1 & 8\end{bmatrix}, then

Match the LIST-I with LIST-II

LIST-ILIST-II
A.∣A∣\vert A \vertI.3838
B.Cofactor of a31a_{31}II.−23-23
C.Minor of a23a_{23}III.−83-83
D.Cofactor of a12a_{12}IV.−13-13

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 3

∣A∣=12(22)−7(38)+9(−9)=264−266−81=−83|A| = 12(22) - 7(38) + 9(-9) = 264 - 266 - 81 = -83 (III).

Cofactor of a31=+(7⋅2−9⋅3)=−13a_{31} = +(7\cdot2 - 9\cdot3) = -13 (IV).

Minor of a23=12−35=−23a_{23} = 12 - 35 = -23 (II).

Minor of a12=48−10=38a_{12} = 48 - 10 = 38 (I).

Note: LIST-I labels the last entry as the cofactor of a12a_{12}, which is −38-38; the matching value 3838 is its minor, and we have matched accordingly. This is an error from NTA's side!

Solution figure for CUET Mathematics 2026 21 May Shift 2 question 70 (Algebra)

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