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If A=[0l−3−201m−10]A = \begin{bmatrix} 0 & l & -3 \\ -2 & 0 & 1 \\ m & -1 & 0 \end{bmatrix} is a skew symmetric matrix, then

Solution

✅ Correct Option: 3

A skew symmetric matrix satisfies AT=−AA^T = -A.

This means the transpose equals the negative of the original matrix.

For any skew symmetric matrix:

  • All diagonal elements must be 0
  • Elements satisfy aij=−ajia_{ij} = -a_{ji}

For position (1,2)(1,2) and position (2,1)(2,1):

Position (1,2)=l(1,2) = l

Position (2,1)=−2(2,1) = -2

Using the property aij=−ajia_{ij} = -a_{ji}:

l=−(−2)l = -(-2)

l=2l = 2


For position (1,3)(1,3) and position (3,1)(3,1):

Position (1,3)=−3(1,3) = -3

Position (3,1)=m(3,1) = m

Using the property aij=−ajia_{ij} = -a_{ji}:

−3=−m-3 = -m

m=3m = 3


Therefore, l=2l = 2 and m=3m = 3.

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