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If A=[(1,x),(x^(2),4y)] and B=[(-3,1),(1...

If `A=[(1,x),(x^(2),4y)]` and `B=[(-3,1),(1,0)], adj(A)+B=[(1,0),(0,1)]` then the values of `x` and `y` are

A

1,1

B

`+-1,1`

C

1,0

D

None of these

Text Solution

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The correct Answer is:
To solve the problem, we need to find the values of \( x \) and \( y \) given the matrices \( A \) and \( B \) and the equation involving their adjoint. Let's break it down step by step. ### Step 1: Define the Matrices The matrix \( A \) is given as: \[ A = \begin{pmatrix} 1 & x \\ x^2 & 4y \end{pmatrix} \] The matrix \( B \) is given as: \[ B = \begin{pmatrix} -3 & 1 \\ 1 & 0 \end{pmatrix} \] ### Step 2: Find the Adjoint of Matrix \( A \) The adjoint of a matrix is the transpose of its cofactor matrix. We will first find the cofactors of matrix \( A \). - The cofactor \( C_{11} \) is the determinant of the submatrix obtained by removing the first row and first column: \[ C_{11} = 4y \] - The cofactor \( C_{12} \) is: \[ C_{12} = -x^2 \] - The cofactor \( C_{21} \) is: \[ C_{21} = -x \] - The cofactor \( C_{22} \) is: \[ C_{22} = 1 \] Thus, the cofactor matrix \( C \) is: \[ C = \begin{pmatrix} 4y & -x^2 \\ -x & 1 \end{pmatrix} \] Now, we take the transpose of the cofactor matrix to find the adjoint of \( A \): \[ \text{adj}(A) = C^T = \begin{pmatrix} 4y & -x \\ -x^2 & 1 \end{pmatrix} \] ### Step 3: Set Up the Equation We know from the problem that: \[ \text{adj}(A) + B = \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix} \] Substituting the matrices, we have: \[ \begin{pmatrix} 4y & -x \\ -x^2 & 1 \end{pmatrix} + \begin{pmatrix} -3 & 1 \\ 1 & 0 \end{pmatrix} = \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix} \] ### Step 4: Combine the Matrices Now we combine the matrices: \[ \begin{pmatrix} 4y - 3 & -x + 1 \\ -x^2 + 1 & 1 \end{pmatrix} = \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix} \] ### Step 5: Set Up the System of Equations From the above matrix equation, we can set up the following equations: 1. \( 4y - 3 = 1 \) 2. \( -x + 1 = 0 \) 3. \( -x^2 + 1 = 0 \) 4. \( 1 = 1 \) (This is always true and does not provide any new information) ### Step 6: Solve the Equations **From Equation 2:** \[ -x + 1 = 0 \implies x = 1 \] **From Equation 1:** \[ 4y - 3 = 1 \implies 4y = 4 \implies y = 1 \] ### Final Values Thus, the values of \( x \) and \( y \) are: \[ x = 1, \quad y = 1 \] ### Summary The final answer is: \[ (x, y) = (1, 1) \]

To solve the problem, we need to find the values of \( x \) and \( y \) given the matrices \( A \) and \( B \) and the equation involving their adjoint. Let's break it down step by step. ### Step 1: Define the Matrices The matrix \( A \) is given as: \[ A = \begin{pmatrix} 1 & x \\ x^2 & 4y \end{pmatrix} \] The matrix \( B \) is given as: ...
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