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The matrix A=[−3000−3000−3]A = \begin{bmatrix}-3 & 0 & 0\\0 & -3 & 0\\0 & 0 & -3\end{bmatrix} is a

A. Symmetric matrix

B. Scalar matrix

C. Diagonal matrix

D. Skew-symmetric matrix

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 1

Here A=−3IA = -3I: all off-diagonal entries are zero, so it is diagonal, and the equal diagonal entries make it scalar.

Since AT=AA^T = A, it is symmetric. A skew-symmetric matrix needs zero diagonal entries, so D fails. Hence A, B and C.

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