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Which of the following are correct?

(A) A=[−94−3−104220]A=\begin{bmatrix}-9 & 4 & -3\\-1 & 0 & 4\\2 & 2 & 0\end{bmatrix} ; a22+a32=−9a_{22}+a_{32}=-9 where aija_{ij} denotes the (i,j)th(i,j)^{th} element of matrix A.

(B) A=[2−2−22]A=\begin{bmatrix}2 & -2\\-2 & 2\end{bmatrix}; A2=pAA^2=pA, then p=4p=4

(C) [86616]\begin{bmatrix}8 & 6\\6 & 16\end{bmatrix} is a symmetric matrix

(D) [0−5350−7−370]\begin{bmatrix}0 & -5 & 3\\5 & 0 & -7\\-3 & 7 & 0\end{bmatrix} is a symmetric matrix

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 3

(B): A2=[8−8−88]=4AA^2=\begin{bmatrix}8&-8\\-8&8\end{bmatrix}=4A, so p=4p=4 and it is true. (C): the matrix equals its own transpose, so it is symmetric, true.

(A) is false because a22+a32=0+2=2a_{22}+a_{32}=0+2=2, and (D) is false because that matrix is skew-symmetric, not symmetric.

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