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Let A=[(1,1,1),(1,-1,0),(0,1,-1)], A(1) ...

Let `A=[(1,1,1),(1,-1,0),(0,1,-1)], A_(1)` be a matrix formed by the cofactors of the elements of the matrix A and `A_(2)` be a matrix formed by the cofactors of the elements of matrix `A_(1)`. Similarly, If `A_(10)` be a matrrix formed by the cofactors of the elements of matrix `A_(9)`, then the value of `|A_(10)|` is

A

`3^(10)`

B

`3^(20)`

C

9

D

`3^(1024)`

Text Solution

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The correct Answer is:
To solve the problem, we need to find the determinant of the matrix \( A_{10} \) formed by the cofactors of the elements of the matrix \( A_{9} \). We will use the property of determinants related to cofactors. ### Step-by-Step Solution: 1. **Calculate the Determinant of Matrix \( A \)**: Given the matrix: \[ A = \begin{pmatrix} 1 & 1 & 1 \\ 1 & -1 & 0 \\ 0 & 1 & -1 \end{pmatrix} \] We can calculate the determinant using the formula: \[ |A| = a(ei - fh) - b(di - fg) + c(dh - eg) \] Expanding along the first row: \[ |A| = 1 \cdot \begin{vmatrix} -1 & 0 \\ 1 & -1 \end{vmatrix} - 1 \cdot \begin{vmatrix} 1 & 0 \\ 0 & -1 \end{vmatrix} + 1 \cdot \begin{vmatrix} 1 & -1 \\ 0 & 1 \end{vmatrix} \] Calculating the minors: \[ |A| = 1 \cdot (-1 \cdot -1 - 0 \cdot 1) - 1 \cdot (1 \cdot -1 - 0 \cdot 0) + 1 \cdot (1 \cdot 1 - 0 \cdot -1) \] \[ = 1 \cdot 1 - 1 \cdot (-1) + 1 \cdot 1 = 1 + 1 + 1 = 3 \] 2. **Apply the Cofactor Property**: The property states that if \( B \) is formed by the cofactors of \( A \), then: \[ |B| = |A|^2 \] Therefore, we can write: \[ |A_1| = |A|^2 = 3^2 = 9 \] 3. **Continue Applying the Property**: Similarly, for \( A_2 \): \[ |A_2| = |A_1|^2 = 9^2 = 81 \] For \( A_3 \): \[ |A_3| = |A_2|^2 = 81^2 = 6561 \] 4. **Generalize the Pattern**: Continuing this process, we can see a pattern emerging: \[ |A_n| = |A|^{2^n} \] Specifically, we have: \[ |A_1| = 3^{2^1}, \quad |A_2| = 3^{2^2}, \quad |A_3| = 3^{2^3}, \quad \ldots \] Thus, for \( A_{10} \): \[ |A_{10}| = |A|^{2^{10}} = 3^{2^{10}} = 3^{1024} \] 5. **Final Answer**: Therefore, the value of \( |A_{10}| \) is: \[ |A_{10}| = 3^{1024} \]
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