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|adjA|=|A|^(2) where A is a square matri...

`|adjA|=|A|^(2)` where A is a square matrix of order two.

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To prove the statement \(|\text{adj} A| = |A|^2\) for a square matrix \(A\) of order 2, we will follow these steps: ### Step 1: Understand the properties of the adjoint matrix The adjoint (or adjugate) of a matrix \(A\), denoted as \(\text{adj} A\), is defined as the transpose of the cofactor matrix of \(A\). For any square matrix \(A\) of order \(n\), the determinant of the adjoint matrix can be expressed as: \[ |\text{adj} A| = |A|^{n-1} \] where \(n\) is the order of the matrix \(A\). ### Step 2: Apply the formula to a 2x2 matrix Since \(A\) is a square matrix of order 2, we have \(n = 2\). Therefore, we can substitute \(n\) into the formula: \[ |\text{adj} A| = |A|^{2-1} = |A|^1 = |A| \] ### Step 3: Compare with the given statement The statement we need to verify is: \[ |\text{adj} A| = |A|^2 \] From our calculation, we found that: \[ |\text{adj} A| = |A| \] This implies: \[ |A| = |A|^2 \] ### Step 4: Analyze the implications The equation \(|A| = |A|^2\) can be rearranged to: \[ |A|^2 - |A| = 0 \] Factoring gives: \[ |A|(|A| - 1) = 0 \] This means that either \(|A| = 0\) or \(|A| = 1\). ### Conclusion Thus, the statement \(|\text{adj} A| = |A|^2\) holds true only under specific conditions (i.e., when \(|A| = 0\) or \(|A| = 1\)). Therefore, the general statement is not valid for all 2x2 matrices. ### Final Result The statement \(|\text{adj} A| = |A|^2\) is **false** for a general square matrix of order 2. ---

To prove the statement \(|\text{adj} A| = |A|^2\) for a square matrix \(A\) of order 2, we will follow these steps: ### Step 1: Understand the properties of the adjoint matrix The adjoint (or adjugate) of a matrix \(A\), denoted as \(\text{adj} A\), is defined as the transpose of the cofactor matrix of \(A\). For any square matrix \(A\) of order \(n\), the determinant of the adjoint matrix can be expressed as: \[ |\text{adj} A| = |A|^{n-1} \] where \(n\) is the order of the matrix \(A\). ...
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