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Let D(x)=|{:(x^2+4x-3, 2x+4,13),(2x^2+5x...

Let `D(x)=|{:(x^2+4x-3, 2x+4,13),(2x^2+5x-9,4x+5,26),(8x^2-16x+1, 16x-6, 104):}|=alphax^3+betax^2 + gammax+delta` then :

A

`alpha+beta=0`

B

`beta+gamma=0`

C

`alpha+beta+gamma+delta=0`

D

`alpha + beta+ gamma =0`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem, we need to evaluate the determinant \( D(x) \) and express it in the form \( \alpha x^3 + \beta x^2 + \gamma x + \delta \). Let's go through the steps systematically. ### Step 1: Write down the determinant We start with the determinant given in the problem: \[ D(x) = \begin{vmatrix} x^2 + 4x - 3 & 2x + 4 & 13 \\ 2x^2 + 5x - 9 & 4x + 5 & 26 \\ 8x^2 - 16x + 1 & 16x - 6 & 104 \end{vmatrix} \] ### Step 2: Differentiate the determinant To find \( D'(x) \), we will differentiate the determinant with respect to \( x \). We can use the property of determinants that allows us to differentiate each column: 1. Differentiate the first column: - The derivative of \( x^2 + 4x - 3 \) is \( 2x + 4 \). - The derivative of \( 2x^2 + 5x - 9 \) is \( 4x + 5 \). - The derivative of \( 8x^2 - 16x + 1 \) is \( 16x - 16 \). 2. The second and third columns remain unchanged for this differentiation. Thus, we have: \[ D'(x) = \begin{vmatrix} 2x + 4 & 2x + 4 & 13 \\ 4x + 5 & 4x + 5 & 26 \\ 16x - 16 & 16x - 6 & 104 \end{vmatrix} \] ### Step 3: Simplify the determinant Notice that the first two columns of the determinant are identical: \[ D'(x) = \begin{vmatrix} 2x + 4 & 2x + 4 & 13 \\ 4x + 5 & 4x + 5 & 26 \\ 16x - 16 & 16x - 6 & 104 \end{vmatrix} \] Since two columns of a determinant are the same, the value of the determinant is zero: \[ D'(x) = 0 \] ### Step 4: Conclude about \( D(x) \) Since the derivative \( D'(x) = 0 \), it implies that \( D(x) \) is a constant function. Therefore, we can express \( D(x) \) as: \[ D(x) = C \] where \( C \) is a constant. ### Step 5: Identify coefficients From the expression \( D(x) = \alpha x^3 + \beta x^2 + \gamma x + \delta \), since \( D(x) \) is constant, we have: - \( \alpha = 0 \) - \( \beta = 0 \) - \( \gamma = 0 \) - \( \delta = C \) ### Step 6: Calculate the required sums Now we can calculate the required sums: 1. \( \lambda + 1 = C + 1 \) 2. \( \lambda + \beta = C + 0 = C \) 3. \( \beta + \gamma = 0 + 0 = 0 \) 4. \( \alpha + \beta + \gamma = 0 + 0 + 0 = 0 \) ### Final Answer Thus, the values of the sums are: - \( \lambda + 1 = C + 1 \) - \( \lambda + \beta = C \) - \( \beta + \gamma = 0 \) - \( \alpha + \beta + \gamma = 0 \)
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