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Let A be a square matrix of order n. S...

Let A be a square matrix of order n.
Statement - 1 : `abs(adj(adj A))=absA^(n-1)^2`
Statement -2 : `adj(adj A)=absA^(n-2)A`

A

Statement -1 is True, Statement -2 is true, Statement -2 is a correct explanation for Statement-1.

B

Statement-1 is True, Statement -2 is True, Statement -2 is not a correct explanation for Statement -1.

C

Statement -1 is True, Statement -2 is False.

D

Statement -1 is False, Statement -2 is True.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to verify both statements regarding the adjoint of a square matrix \( A \) of order \( n \). ### Step 1: Understanding the adjoint of a matrix The adjoint of a matrix \( A \), denoted as \( \text{adj}(A) \), is defined as the transpose of the cofactor matrix of \( A \). For a square matrix \( A \) of order \( n \), the following properties hold: - \( \text{adj}(A) \cdot A = \det(A) I_n \), where \( I_n \) is the identity matrix of order \( n \). - \( \det(\text{adj}(A)) = \det(A)^{n-1} \). ### Step 2: Analyzing Statement 1 We need to verify if \( |\text{adj}(\text{adj}(A))| = |\det(A)|^{(n-1)^2} \). Using the property of determinants: \[ \det(\text{adj}(A)) = \det(A)^{n-1} \] Now, applying the adjoint operation again: \[ \det(\text{adj}(\text{adj}(A))) = \det(\text{adj}(A))^{n-1} = (\det(A)^{n-1})^{n-1} = \det(A)^{(n-1)^2} \] Thus, we have: \[ |\text{adj}(\text{adj}(A))| = |\det(A)|^{(n-1)^2} \] This confirms that Statement 1 is true. ### Step 3: Analyzing Statement 2 Now we need to verify if \( \text{adj}(\text{adj}(A)) = |\det(A)|^{(n-2)} A \). From the property of adjoints, we know: \[ \text{adj}(\text{adj}(A)) = \det(A)^{n-2} A \] This is derived from the fact that the adjoint of the adjoint of a matrix is proportional to the original matrix scaled by the determinant raised to the power of \( n-2 \). Thus, Statement 2 is also true. ### Conclusion Both statements are true: 1. \( |\text{adj}(\text{adj}(A))| = |\det(A)|^{(n-1)^2} \) 2. \( \text{adj}(\text{adj}(A)) = |\det(A)|^{(n-2)} A \)

To solve the problem, we need to verify both statements regarding the adjoint of a square matrix \( A \) of order \( n \). ### Step 1: Understanding the adjoint of a matrix The adjoint of a matrix \( A \), denoted as \( \text{adj}(A) \), is defined as the transpose of the cofactor matrix of \( A \). For a square matrix \( A \) of order \( n \), the following properties hold: - \( \text{adj}(A) \cdot A = \det(A) I_n \), where \( I_n \) is the identity matrix of order \( n \). - \( \det(\text{adj}(A)) = \det(A)^{n-1} \). ### Step 2: Analyzing Statement 1 ...
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