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If A=[aij]3×3A = [a_{ij}]_{3 \times 3} and aij=i−ja_{ij} = i - j, then which of the following statements are TRUE?

(A). AA is scalar matrix

(B). AA is skew symmetric matrix

(C). ∣A∣=0|A| = 0

(D). a21+a12=0a_{21} + a_{12} = 0

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

Here A=[0−1−210−1210]A=\begin{bmatrix}0&-1&-2\\1&0&-1\\2&1&0\end{bmatrix}. It is not scalar, so (A) is false. Since aij=i−j=−(j−i)=−ajia_{ij}=i-j=-(j-i)=-a_{ji}, it is skew symmetric, so (B) is true. A skew-symmetric matrix of odd order has zero determinant, so (C) is true. Also a21+a12=1−1=0a_{21}+a_{12}=1-1=0, so (D) is true.

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