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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 `det(A)=(1)/(sqrt(3))` then `det(Adj(-2A^(-2)))` is equal to

A

24

B

16

C

576

D

144

Text Solution

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The correct Answer is:
To solve the problem, we need to find the value of \( \det(\text{Adj}(-2A^{-2})) \) given that \( \det(A) = \frac{1}{\sqrt{3}} \) 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 \( B \) is given by the formula: \[ \det(\text{Adj}(B)) = (\det(B))^{n-1} \] where \( n \) is the order of the matrix. Since \( A \) is a \( 3 \times 3 \) matrix, we have \( n = 3 \). 2. **Finding the Determinant of \( -2A^{-2} \)**: We first need to find \( \det(-2A^{-2}) \): \[ \det(-2A^{-2}) = \det(-2I) \cdot \det(A^{-2}) \] where \( I \) is the identity matrix. The determinant of \( -2I \) for a \( 3 \times 3 \) matrix is: \[ \det(-2I) = (-2)^3 = -8 \] 3. **Calculating \( \det(A^{-2}) \)**: We know that: \[ \det(A^{-2}) = \det(A^{-1})^2 = \left(\frac{1}{\det(A)}\right)^2 \] Given \( \det(A) = \frac{1}{\sqrt{3}} \), we find: \[ \det(A^{-1}) = \sqrt{3} \] Therefore: \[ \det(A^{-2}) = (\sqrt{3})^2 = 3 \] 4. **Combining the Determinants**: Now we can combine the results: \[ \det(-2A^{-2}) = -8 \cdot 3 = -24 \] 5. **Finding the Determinant of the Adjoint**: Using the formula for the determinant of the adjoint: \[ \det(\text{Adj}(-2A^{-2})) = (\det(-2A^{-2}))^{3-1} = (-24)^{2} \] Calculating this gives: \[ (-24)^2 = 576 \] ### Final Answer: Thus, the value of \( \det(\text{Adj}(-2A^{-2})) \) is \( \boxed{576} \).

To solve the problem, we need to find the value of \( \det(\text{Adj}(-2A^{-2})) \) given that \( \det(A) = \frac{1}{\sqrt{3}} \) 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 \( B \) is given by the formula: \[ \det(\text{Adj}(B)) = (\det(B))^{n-1} ...
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