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Consider A and B as 2xx2 matrices with d...

Consider `A` and `B` as `2xx2` matrices with determinant equal to 1 then
`tr(AB)-tr(A).tr(B)+tr(AB^(-1))+2` is_______

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To solve the problem, we need to evaluate the expression \( \text{tr}(AB) - \text{tr}(A) \cdot \text{tr}(B) + \text{tr}(AB^{-1}) + 2 \) given that \( A \) and \( B \) are \( 2 \times 2 \) matrices with \( \det(A) = 1 \) and \( \det(B) = 1 \). ### Step-by-Step Solution: 1. **Understanding the Properties of Trace and Determinant**: - The determinant of a \( 2 \times 2 \) matrix \( A \) can be expressed as \( \det(A) = ad - bc \) for a matrix of the form \( \begin{pmatrix} a & b \\ c & d \end{pmatrix} \). - The trace of a matrix \( A \), denoted \( \text{tr}(A) \), is the sum of its diagonal elements, \( \text{tr}(A) = a + d \). 2. **Using the Given Condition**: - Since \( \det(A) = 1 \) and \( \det(B) = 1 \), we can use the property of determinants and traces in \( 2 \times 2 \) matrices. 3. **Evaluating \( \text{tr}(AB^{-1}) \)**: - We know that \( B^{-1} \) exists since \( \det(B) \neq 0 \). - The trace of the product of matrices has the cyclic property: \( \text{tr}(AB) = \text{tr}(BA) \). - Therefore, \( \text{tr}(AB^{-1}) = \text{tr}(A \cdot B^{-1}) \). 4. **Setting Up the Expression**: - We need to evaluate: \[ \text{tr}(AB) - \text{tr}(A) \cdot \text{tr}(B) + \text{tr}(AB^{-1}) + 2 \] 5. **Using the Identity**: - From the properties of traces and determinants, we can derive that: \[ \text{tr}(AB) - \text{tr}(A) \cdot \text{tr}(B) + \text{tr}(AB^{-1}) = 0 \] - This means that: \[ \text{tr}(AB) - \text{tr}(A) \cdot \text{tr}(B) + \text{tr}(AB^{-1}) = 0 \] 6. **Final Calculation**: - Adding 2 to both sides of the equation gives: \[ 0 + 2 = 2 \] ### Conclusion: Thus, the value of the expression \( \text{tr}(AB) - \text{tr}(A) \cdot \text{tr}(B) + \text{tr}(AB^{-1}) + 2 \) is \( \boxed{2} \).

To solve the problem, we need to evaluate the expression \( \text{tr}(AB) - \text{tr}(A) \cdot \text{tr}(B) + \text{tr}(AB^{-1}) + 2 \) given that \( A \) and \( B \) are \( 2 \times 2 \) matrices with \( \det(A) = 1 \) and \( \det(B) = 1 \). ### Step-by-Step Solution: 1. **Understanding the Properties of Trace and Determinant**: - The determinant of a \( 2 \times 2 \) matrix \( A \) can be expressed as \( \det(A) = ad - bc \) for a matrix of the form \( \begin{pmatrix} a & b \\ c & d \end{pmatrix} \). - The trace of a matrix \( A \), denoted \( \text{tr}(A) \), is the sum of its diagonal elements, \( \text{tr}(A) = a + d \). ...
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