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If `alpha and beta` are the roots of the equation, `[1,5][(1,3),(-4,7)]^(2)[(7/19, -13/19),(4/19,1/19)]^(4)`
`[(1,3),(-4,7)]^(2)[(x^2 - 5x + 5),(-3)] = [-4]`, then the value of `(2 - alpha)(2 - beta)` is

A

51

B

`-12`

C

`12`

D

`-7`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we will first rewrite the equation and then find the roots, followed by calculating the desired expression. ### Step 1: Rewrite the equation The equation given is: \[ [(1, 5)][(1, 3), (-4, 7)]^2 \left[(\frac{7}{19}, -\frac{13}{19}), (\frac{4}{19}, \frac{1}{19})\right]^4 \left[(1, 3), (-4, 7)]^2 \left[(x^2 - 5x + 5), -3\right] = -4 \] ### Step 2: Simplify the matrix expressions We need to compute the determinants and adjoints of the matrices involved. For the matrix \( A = \begin{pmatrix} 1 & 3 \\ -4 & 7 \end{pmatrix} \): - The determinant \( |A| = (1)(7) - (3)(-4) = 7 + 12 = 19 \). - The adjoint of \( A \) is \( \text{adj}(A) = \begin{pmatrix} 7 & -3 \\ 4 & 1 \end{pmatrix} \). ### Step 3: Find \( A^{-1} \) Using the formula for the inverse of a 2x2 matrix: \[ A^{-1} = \frac{1}{|A|} \text{adj}(A) = \frac{1}{19} \begin{pmatrix} 7 & -3 \\ 4 & 1 \end{pmatrix} \] ### Step 4: Substitute back into the equation Now substitute \( A \) and \( A^{-1} \) back into the equation. The left-hand side simplifies to: \[ \frac{1}{19} \begin{pmatrix} 7 & -3 \\ 4 & 1 \end{pmatrix} \begin{pmatrix} 1 & 3 \\ -4 & 7 \end{pmatrix}^2 \left[(x^2 - 5x + 5), -3\right] = -4 \] ### Step 5: Solve for \( x \) After simplifying and rearranging the equation, we arrive at: \[ x^2 - 5x - 6 = 0 \] This factors to: \[ (x - 6)(x + 1) = 0 \] Thus, the roots are \( x = 6 \) and \( x = -1 \). ### Step 6: Identify \( \alpha \) and \( \beta \) Let \( \alpha = 6 \) and \( \beta = -1 \). ### Step 7: Calculate \( (2 - \alpha)(2 - \beta) \) Now we need to find: \[ (2 - \alpha)(2 - \beta) = (2 - 6)(2 + 1) = (-4)(3) = -12 \] ### Final Answer The value of \( (2 - \alpha)(2 - \beta) \) is \( -12 \).
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