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Let A and B two symmetric matrices of or...

Let A and B two symmetric matrices of order 3.
Statement 1 : `A(BA)` and `(AB)A` are symmetric matrices.
Statement 2 : `AB` is symmetric matrix if matrix multiplication of A with B is commutative.

A

Statement 1 is false, statement 2 is true.

B

Statement 1 is true, statement 2 is true, statement 2 is a correct explanation for statement 1.

C

Statement 1 is true, statement 2 is true, statement 2 is not a correct explanation for statement 1.

D

Statement 1 is true, statement 2 is false.

Text Solution

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To solve the problem, we need to analyze the two statements about symmetric matrices \( A \) and \( B \) of order 3. ### Step 1: Understanding Symmetric Matrices A matrix \( A \) is symmetric if \( A = A^T \), where \( A^T \) denotes the transpose of matrix \( A \). Similarly, \( B \) is symmetric if \( B = B^T \). ### Step 2: Proving Statement 1: \( A(BA) \) and \( (AB)A \) are symmetric matrices 1. **For \( A(BA) \)**: - We need to find the transpose of \( A(BA) \): \[ (A(BA))^T = (BA)^T A^T \] - Using the property of transpose, \( (XY)^T = Y^T X^T \): \[ (BA)^T = A^T B^T \] - Since both \( A \) and \( B \) are symmetric: \[ (BA)^T = A B \] - Therefore: \[ (A(BA))^T = (AB)A \] - Thus, \( A(BA) = (AB)A \), which shows that \( A(BA) \) is symmetric. 2. **For \( (AB)A \)**: - We need to find the transpose of \( (AB)A \): \[ ((AB)A)^T = A^T (AB)^T \] - Again using the property of transpose: \[ (AB)^T = B^T A^T \] - Since both \( A \) and \( B \) are symmetric: \[ (AB)^T = BA \] - Therefore: \[ ((AB)A)^T = A (BA) \] - Thus, \( (AB)A = A(BA) \), which shows that \( (AB)A \) is symmetric. ### Conclusion for Statement 1: Both \( A(BA) \) and \( (AB)A \) are symmetric matrices. Therefore, Statement 1 is **true**. ### Step 3: Proving Statement 2: \( AB \) is symmetric if \( AB = BA \) - We need to check if \( AB \) is symmetric under the condition \( AB = BA \): \[ (AB)^T = B^T A^T \] - Since \( A \) and \( B \) are symmetric: \[ (AB)^T = BA \] - Given that \( AB = BA \): \[ (AB)^T = AB \] - Thus, \( AB \) is symmetric. ### Conclusion for Statement 2: Statement 2 is also **true**. ### Final Conclusion: Both statements are true.

To solve the problem, we need to analyze the two statements about symmetric matrices \( A \) and \( B \) of order 3. ### Step 1: Understanding Symmetric Matrices A matrix \( A \) is symmetric if \( A = A^T \), where \( A^T \) denotes the transpose of matrix \( A \). Similarly, \( B \) is symmetric if \( B = B^T \). ### Step 2: Proving Statement 1: \( A(BA) \) and \( (AB)A \) are symmetric matrices 1. **For \( A(BA) \)**: - We need to find the transpose of \( A(BA) \): ...
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