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Find the inverse of the matrix [{:(-3,2)...

Find the inverse of the matrix `[{:(-3,2),(5,-3):}]` Hence, find the matrix `P` satisfying the matrix equation :
`P[{:(-3,2),(5,-3):}]=[{:(1,2),(2,-1):}]`

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The correct Answer is:
To solve the problem, we need to find the inverse of the matrix \( A = \begin{pmatrix} -3 & 2 \\ 5 & -3 \end{pmatrix} \) and then use this inverse to find the matrix \( P \) that satisfies the equation \( P A = B \), where \( B = \begin{pmatrix} 1 & 2 \\ 2 & -1 \end{pmatrix} \). ### Step 1: Find the determinant of matrix \( A \) The determinant of a 2x2 matrix \( \begin{pmatrix} a & b \\ c & d \end{pmatrix} \) is calculated as: \[ \text{det}(A) = ad - bc \] For our matrix \( A \): - \( a = -3 \) - \( b = 2 \) - \( c = 5 \) - \( d = -3 \) Calculating the determinant: \[ \text{det}(A) = (-3)(-3) - (2)(5) = 9 - 10 = -1 \] ### Step 2: Find the adjoint of matrix \( A \) The adjoint of a 2x2 matrix \( \begin{pmatrix} a & b \\ c & d \end{pmatrix} \) is given by: \[ \text{adj}(A) = \begin{pmatrix} d & -b \\ -c & a \end{pmatrix} \] For our matrix \( A \): \[ \text{adj}(A) = \begin{pmatrix} -3 & -2 \\ -5 & -3 \end{pmatrix} \] ### Step 3: Find the inverse of matrix \( A \) The inverse of a matrix \( A \) is given by: \[ A^{-1} = \frac{1}{\text{det}(A)} \cdot \text{adj}(A) \] Substituting the values we found: \[ A^{-1} = \frac{1}{-1} \cdot \begin{pmatrix} -3 & -2 \\ -5 & -3 \end{pmatrix} = \begin{pmatrix} 3 & 2 \\ 5 & 3 \end{pmatrix} \] ### Step 4: Find the matrix \( P \) We know from the equation \( P A = B \) that: \[ P = B A^{-1} \] Substituting the matrices \( B \) and \( A^{-1} \): \[ B = \begin{pmatrix} 1 & 2 \\ 2 & -1 \end{pmatrix}, \quad A^{-1} = \begin{pmatrix} 3 & 2 \\ 5 & 3 \end{pmatrix} \] Now we will calculate \( P \): \[ P = \begin{pmatrix} 1 & 2 \\ 2 & -1 \end{pmatrix} \begin{pmatrix} 3 & 2 \\ 5 & 3 \end{pmatrix} \] Calculating the elements of \( P \): - First row, first column: \( 1 \cdot 3 + 2 \cdot 5 = 3 + 10 = 13 \) - First row, second column: \( 1 \cdot 2 + 2 \cdot 3 = 2 + 6 = 8 \) - Second row, first column: \( 2 \cdot 3 + (-1) \cdot 5 = 6 - 5 = 1 \) - Second row, second column: \( 2 \cdot 2 + (-1) \cdot 3 = 4 - 3 = 1 \) Thus, we have: \[ P = \begin{pmatrix} 13 & 8 \\ 1 & 1 \end{pmatrix} \] ### Final Answer The inverse of the matrix \( A \) is: \[ A^{-1} = \begin{pmatrix} 3 & 2 \\ 5 & 3 \end{pmatrix} \] And the matrix \( P \) is: \[ P = \begin{pmatrix} 13 & 8 \\ 1 & 1 \end{pmatrix} \]
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Knowledge Check

  • The inverse of the matrix [ (5,-2),(3,1)] is

    A
    `(1)/(11) [(1,2),(-3,5)]`
    B
    `[(1,2),(-3,5)]`
    C
    `(1)/(13)[(-2,5),(1,3)]`
    D
    `[(1,3),(-2,5)]`
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