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If A is a square matrix of order 3 such ...

If `A` is a square matrix of order `3` such that `|A|=2`, then `|(adjA^(-1))^(-1)|` is

A

`1`

B

`2`

C

`4`

D

`8`

Text Solution

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The correct Answer is:
To solve the problem, we need to find the value of \( |(adj A^{-1})^{-1}| \) given that \( |A| = 2 \) and \( A \) is a square matrix of order 3. ### Step-by-Step Solution: 1. **Understanding the Determinant of the Adjoint**: The determinant of the adjoint of a matrix \( A \) can be expressed as: \[ |adj A| = |A|^{n-1} \] where \( n \) is the order of the matrix. Since \( A \) is a \( 3 \times 3 \) matrix, \( n = 3 \). Therefore: \[ |adj A| = |A|^{3-1} = |A|^2 \] 2. **Calculating the Determinant of the Adjoint of the Inverse**: We know that: \[ |A| = 2 \] Thus: \[ |adj A| = |A|^2 = 2^2 = 4 \] 3. **Finding the Determinant of the Inverse**: The determinant of the inverse of a matrix is given by: \[ |A^{-1}| = \frac{1}{|A|} \] Therefore: \[ |A^{-1}| = \frac{1}{2} \] 4. **Finding the Determinant of the Adjoint of the Inverse**: We apply the formula for the adjoint again: \[ |adj A^{-1}| = |A^{-1}|^{n-1} = |A^{-1}|^{3-1} = |A^{-1}|^2 \] Substituting the value we found: \[ |adj A^{-1}| = \left(\frac{1}{2}\right)^2 = \frac{1}{4} \] 5. **Finding the Determinant of the Inverse of the Adjoint**: Finally, we need to find \( |(adj A^{-1})^{-1}| \): \[ |(adj A^{-1})^{-1}| = \frac{1}{|adj A^{-1}|} \] Therefore: \[ |(adj A^{-1})^{-1}| = \frac{1}{\frac{1}{4}} = 4 \] ### Final Answer: Thus, the value of \( |(adj A^{-1})^{-1}| \) is \( 4 \).

To solve the problem, we need to find the value of \( |(adj A^{-1})^{-1}| \) given that \( |A| = 2 \) and \( A \) is a square matrix of order 3. ### Step-by-Step Solution: 1. **Understanding the Determinant of the Adjoint**: The determinant of the adjoint of a matrix \( A \) can be expressed as: \[ |adj A| = |A|^{n-1} ...
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