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Given: \(A^{-1} = \frac{1}{7}\begin{bmatrix} 2 & 1 \\ -3 & 2 \end{bmatrix}\)
To find matrix A, we need to find the inverse of \(A^{-1}\).
Let \(B = A^{-1} = \frac{1}{7}\begin{bmatrix} 2 & 1 \\ -3 & 2 \end{bmatrix}\)
First, find the determinant of the matrix inside the scalar multiplication:
\(\text{det}\begin{bmatrix} 2 & 1 \\ -3 & 2 \end{bmatrix} = (2 \times 2) - (1 \times -3) = 4 + 3 = 7\)
Now, find the inverse of the matrix inside the scalar multiplication:
\(\begin{bmatrix} 2 & 1 \\ -3 & 2 \end{bmatrix}^{-1} = \frac{1}{7}\begin{bmatrix} 2 & -1 \\ 3 & 2 \end{bmatrix}\)
Since \(B = \frac{1}{7}\begin{bmatrix} 2 & 1 \\ -3 & 2 \end{bmatrix}\), then \(B^{-1} = \left(\frac{1}{7}\begin{bmatrix} 2 & 1 \\ -3 & 2 \end{bmatrix}\right)^{-1} = 7 \begin{bmatrix} 2 & 1 \\ -3 & 2 \end{bmatrix}^{-1} = 7 \cdot \frac{1}{7} \begin{bmatrix} 2 & -1 \\ 3 & 2 \end{bmatrix} = \begin{bmatrix} 2 & -1 \\ 3 & 2 \end{bmatrix}\)
Therefore, \(A = \begin{bmatrix} 2 & -1 \\ 3 & 2 \end{bmatrix}\)
Correct Answer: \(\begin{bmatrix}2&-1\\ 3&2\end{bmatrix}\)
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