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M=[{:(sin^(4)theta,-1-sin^(2)theta),(1+c...

`M=[{:(sin^(4)theta,-1-sin^(2)theta),(1+cos^(2)theta,cos^(4)theta):}]=alphaI+betaM^(-1)`
Where `alpha=alpha(theta)` and `beta=beta(theta)` ar real numbers and I is an identity matric of `2xx2`
if `alpha^(**)=` min of set `{alpha(theta):thetain[0.2pi)}`
and `beta^(**)=` min of set `{beta(theta):thetain[0.2pi)}`
Then value of `alpha^(**)+beta^(**)` is

A

`(-37)/(16)`

B

`(-17)/(16)`

C

`(-31)/(16)`

D

`(-29)/(16)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem step by step, we will analyze the matrix \( M \) and derive the values of \( \alpha^{**} \) and \( \beta^{**} \). ### Step 1: Define the Matrix \( M \) The matrix \( M \) is given as: \[ M = \begin{pmatrix} \sin^4 \theta & -1 - \sin^2 \theta \\ 1 + \cos^2 \theta & \cos^4 \theta \end{pmatrix} \] ### Step 2: Find the Inverse of Matrix \( M \) The inverse of a \( 2 \times 2 \) matrix \( \begin{pmatrix} a & b \\ c & d \end{pmatrix} \) is given by: \[ M^{-1} = \frac{1}{ad - bc} \begin{pmatrix} d & -b \\ -c & a \end{pmatrix} \] First, we need to calculate the determinant \( |M| = ad - bc \). #### Calculation of Determinant: \[ |M| = \sin^4 \theta \cdot \cos^4 \theta - (-1 - \sin^2 \theta)(1 + \cos^2 \theta) \] Expanding this gives: \[ |M| = \sin^4 \theta \cos^4 \theta + (1 + \sin^2 \theta + \cos^2 \theta + \sin^2 \theta \cos^2 \theta) \] Using \( \sin^2 \theta + \cos^2 \theta = 1 \): \[ |M| = \sin^4 \theta \cos^4 \theta + 2 + \sin^2 \theta \cos^2 \theta \] ### Step 3: Substitute \( M \) and \( M^{-1} \) into the Equation Given: \[ M = \alpha I + \beta M^{-1} \] where \( I \) is the identity matrix: \[ I = \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix} \] Substituting \( M \) and \( M^{-1} \) into the equation gives: \[ \begin{pmatrix} \sin^4 \theta & -1 - \sin^2 \theta \\ 1 + \cos^2 \theta & \cos^4 \theta \end{pmatrix} = \alpha \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix} + \beta \cdot \frac{1}{|M|} \begin{pmatrix} \cos^4 \theta & 1 + \sin^2 \theta \\ -1 - \cos^2 \theta & \sin^4 \theta \end{pmatrix} \] ### Step 4: Equate the Elements From the matrix equation, we can equate the corresponding elements to find \( \alpha \) and \( \beta \). 1. For the first element: \[ \sin^4 \theta = \alpha + \frac{\beta \cos^4 \theta}{|M|} \] 2. For the second element: \[ -1 - \sin^2 \theta = \frac{\beta (1 + \sin^2 \theta)}{|M|} \] 3. For the third element: \[ 1 + \cos^2 \theta = -\frac{\beta (1 + \cos^2 \theta)}{|M|} \] 4. For the fourth element: \[ \cos^4 \theta = \alpha + \frac{\beta \sin^4 \theta}{|M|} \] ### Step 5: Solve for \( \alpha \) and \( \beta \) From the equations, we can isolate \( \alpha \) and \( \beta \). After some algebraic manipulation, we find: \[ \alpha = 1 - \frac{1}{2}\sin^2(2\theta) \] \[ \beta = -|M| \] ### Step 6: Find the Minimum Values To find \( \alpha^{**} \) and \( \beta^{**} \): 1. The minimum value of \( \alpha \) occurs when \( \sin^2(2\theta) \) is maximum, which is 1. Thus: \[ \alpha^{**} = 1 - \frac{1}{2} = \frac{1}{2} \] 2. For \( \beta \), we need to calculate \( |M| \) at its maximum value. After evaluating, we find: \[ \beta^{**} = -\frac{37}{16} \] ### Step 7: Calculate \( \alpha^{**} + \beta^{**} \) Finally, we calculate: \[ \alpha^{**} + \beta^{**} = \frac{1}{2} - \frac{37}{16} = \frac{8}{16} - \frac{37}{16} = -\frac{29}{16} \] ### Final Answer: \[ \alpha^{**} + \beta^{**} = -\frac{29}{16} \]

To solve the given problem step by step, we will analyze the matrix \( M \) and derive the values of \( \alpha^{**} \) and \( \beta^{**} \). ### Step 1: Define the Matrix \( M \) The matrix \( M \) is given as: \[ M = \begin{pmatrix} \sin^4 \theta & -1 - \sin^2 \theta \\ 1 + \cos^2 \theta & \cos^4 \theta ...
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