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If A=[(2,-2,-4),(-1,3,4),(1,-2,-3)] and ...

If `A=[(2,-2,-4),(-1,3,4),(1,-2,-3)] and B=[(-4,-3,-3),(1,0,1),(4,4,3)]` are two matrices, then the value of the determinant `(A+A^(2)B^(2)+A^(3)+A^(4)B^(4)+"………"20" terms")`

A

`(20)^(3)`

B

`2(20)^(3)`

C

`-(20)^(3)`

D

0

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To solve the problem, we need to find the determinant of the expression \( A + A^2B^2 + A^3 + A^4B^4 + \ldots \) up to 20 terms, where \( A \) and \( B \) are given matrices. ### Step 1: Calculate \( A^2 \) We start by calculating \( A^2 \) which is \( A \times A \). Given: \[ A = \begin{pmatrix} 2 & -2 & -4 \\ -1 & 3 & 4 \\ 1 & -2 & -3 \end{pmatrix} \] Calculating \( A^2 \): \[ A^2 = A \times A = \begin{pmatrix} 2 & -2 & -4 \\ -1 & 3 & 4 \\ 1 & -2 & -3 \end{pmatrix} \times \begin{pmatrix} 2 & -2 & -4 \\ -1 & 3 & 4 \\ 1 & -2 & -3 \end{pmatrix} \] Calculating each element: - First row, first column: \( 2 \cdot 2 + (-2) \cdot (-1) + (-4) \cdot 1 = 4 + 2 - 4 = 2 \) - First row, second column: \( 2 \cdot (-2) + (-2) \cdot 3 + (-4) \cdot (-2) = -4 - 6 + 8 = -2 \) - First row, third column: \( 2 \cdot (-4) + (-2) \cdot 4 + (-4) \cdot (-3) = -8 - 8 + 12 = -4 \) - Second row, first column: \( -1 \cdot 2 + 3 \cdot (-1) + 4 \cdot 1 = -2 - 3 + 4 = -1 \) - Second row, second column: \( -1 \cdot (-2) + 3 \cdot 3 + 4 \cdot (-2) = 2 + 9 - 8 = 3 \) - Second row, third column: \( -1 \cdot (-4) + 3 \cdot 4 + 4 \cdot (-3) = 4 + 12 - 12 = 4 \) - Third row, first column: \( 1 \cdot 2 + (-2) \cdot (-1) + (-3) \cdot 1 = 2 + 2 - 3 = 1 \) - Third row, second column: \( 1 \cdot (-2) + (-2) \cdot 3 + (-3) \cdot (-2) = -2 - 6 + 6 = -2 \) - Third row, third column: \( 1 \cdot (-4) + (-2) \cdot 4 + (-3) \cdot (-3) = -4 - 8 + 9 = -3 \) So, \[ A^2 = \begin{pmatrix} 2 & -2 & -4 \\ -1 & 3 & 4 \\ 1 & -2 & -3 \end{pmatrix} \] ### Step 2: Calculate \( B^2 \) Next, we calculate \( B^2 \). Given: \[ B = \begin{pmatrix} -4 & -3 & -3 \\ 1 & 0 & 1 \\ 4 & 4 & 3 \end{pmatrix} \] Calculating \( B^2 \): \[ B^2 = B \times B = \begin{pmatrix} -4 & -3 & -3 \\ 1 & 0 & 1 \\ 4 & 4 & 3 \end{pmatrix} \times \begin{pmatrix} -4 & -3 & -3 \\ 1 & 0 & 1 \\ 4 & 4 & 3 \end{pmatrix} \] Calculating each element: - First row, first column: \( -4 \cdot -4 + (-3) \cdot 1 + (-3) \cdot 4 = 16 - 3 - 12 = 1 \) - First row, second column: \( -4 \cdot -3 + (-3) \cdot 0 + (-3) \cdot 4 = 12 + 0 - 12 = 0 \) - First row, third column: \( -4 \cdot -3 + (-3) \cdot 1 + (-3) \cdot 3 = 12 - 3 - 9 = 0 \) - Second row, first column: \( 1 \cdot -4 + 0 \cdot 1 + 1 \cdot 4 = -4 + 0 + 4 = 0 \) - Second row, second column: \( 1 \cdot -3 + 0 \cdot 0 + 1 \cdot 4 = -3 + 0 + 4 = 1 \) - Second row, third column: \( 1 \cdot -3 + 0 \cdot 1 + 1 \cdot 3 = -3 + 0 + 3 = 0 \) - Third row, first column: \( 4 \cdot -4 + 4 \cdot 1 + 3 \cdot 4 = -16 + 4 + 12 = 0 \) - Third row, second column: \( 4 \cdot -3 + 4 \cdot 0 + 3 \cdot 4 = -12 + 0 + 12 = 0 \) - Third row, third column: \( 4 \cdot -3 + 4 \cdot 1 + 3 \cdot 3 = -12 + 4 + 9 = 1 \) So, \[ B^2 = \begin{pmatrix} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{pmatrix} \] This is the identity matrix \( I \). ### Step 3: Analyze the Series Now we can analyze the series: \[ A + A^2B^2 + A^3 + A^4B^4 + \ldots \] Since \( A^2 = A \) and \( B^2 = I \), we can simplify the series: \[ A + A + A + A + \ldots \text{ (20 terms)} \] This simplifies to: \[ 20A \] ### Step 4: Calculate the Determinant Now we need to find the determinant: \[ \text{det}(20A) = 20^3 \cdot \text{det}(A) \] where the factor \( 20^3 \) comes from the property of determinants that states \( \text{det}(kA) = k^n \cdot \text{det}(A) \) for an \( n \times n \) matrix \( A \). ### Step 5: Calculate \( \text{det}(A) \) Now we calculate \( \text{det}(A) \): \[ A = \begin{pmatrix} 2 & -2 & -4 \\ -1 & 3 & 4 \\ 1 & -2 & -3 \end{pmatrix} \] Using the determinant formula for a \( 3 \times 3 \) matrix: \[ \text{det}(A) = a(ei - fh) - b(di - fg) + c(dh - eg) \] where \( A = \begin{pmatrix} a & b & c \\ d & e & f \\ g & h & i \end{pmatrix} \). Calculating: \[ \text{det}(A) = 2(3 \cdot (-3) - 4 \cdot (-2)) - (-2)(-1 \cdot (-3) - 4 \cdot 1) + (-4)(-1 \cdot (-2) - 3 \cdot 1) \] Calculating each term: - First term: \( 2(-9 + 8) = 2(-1) = -2 \) - Second term: \( -2(3 - 4) = -2(-1) = 2 \) - Third term: \( -4(2 - 3) = -4(-1) = 4 \) So, \[ \text{det}(A) = -2 + 2 + 4 = 4 \] ### Step 6: Final Calculation Now substituting back: \[ \text{det}(20A) = 20^3 \cdot 4 = 8000 \] ### Conclusion Thus, the value of the determinant \( A + A^2B^2 + A^3 + A^4B^4 + \ldots \) up to 20 terms is: \[ \boxed{8000} \]
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