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If A And B Are Symmetric Matrices of the Same Order, Write Whether Ab − Ba Is Symmetric Or Skew-symmetric Or Neither of the Two.

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प्रश्न

If A and B are symmetric matrices of the same order, write whether AB − BA is symmetric or skew-symmetric or neither of the two.

योग
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उत्तर

Since A and B are symmetric matrices, \[A^T =\text{ A and }B^T = B\]
Here,

\[\left( AB - BA \right)^T = \left( AB \right)^T - \left( BA \right)^T \] 

\[ \Rightarrow \left( AB - BA \right)^T = B^T A^T - A^T B^T \left[ \because \left( AB \right)^T = B^T A^T \right]\] 

\[ \Rightarrow \left( AB - BA \right)^T = BA - AB \left[ \because B^T = \text{B and}    A^T = A \right]\] 

\[ \Rightarrow \left( AB - BA \right)^T = - \left( AB - BA \right)\] 
Therefore, AB - BA is skew - symmetric .

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  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 4: Algebra of Matrices - Exercise 5.6 [पृष्ठ ६३]

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आर.डी. शर्मा Mathematics Volume 1 and 2 [English] Class 12
अध्याय 4 Algebra of Matrices
Exercise 5.6 | Q 30 | पृष्ठ ६३

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