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Let plamda^(4)+qlamda^(3)+rlamda^(2)+sla...

Let `plamda^(4)+qlamda^(3)+rlamda^(2)+slamda+t`
`=|(lamda^(2)+3lamda,lamda-1,lamda-3),(lamda-1,-2lamda,lamda-4),(lamda-3,lamda+4,3lamda)|`
where p,q,r,s, and t are constant. Then value of t is

A

0

B

`-1`

C

`2`

D

`3`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the equation \[ p \lambda^4 + q \lambda^3 + r \lambda^2 + s \lambda + t = \begin{vmatrix} \lambda^2 + 3\lambda & \lambda - 1 & \lambda - 3 \\ \lambda - 1 & -2\lambda & \lambda - 4 \\ \lambda - 3 & \lambda + 4 & 3\lambda \end{vmatrix} \] we need to find the value of \( t \). ### Step 1: Substitute \( \lambda = 0 \) We start by substituting \( \lambda = 0 \) into both sides of the equation. **LHS:** \[ p(0)^4 + q(0)^3 + r(0)^2 + s(0) + t = t \] **RHS:** \[ \begin{vmatrix} 0^2 + 3(0) & 0 - 1 & 0 - 3 \\ 0 - 1 & -2(0) & 0 - 4 \\ 0 - 3 & 0 + 4 & 3(0) \end{vmatrix} = \begin{vmatrix} 0 & -1 & -3 \\ -1 & 0 & -4 \\ -3 & 4 & 0 \end{vmatrix} \] ### Step 2: Calculate the Determinant Now we need to calculate the determinant: \[ D = \begin{vmatrix} 0 & -1 & -3 \\ -1 & 0 & -4 \\ -3 & 4 & 0 \end{vmatrix} \] Using the determinant formula for a 3x3 matrix: \[ D = a(ei - fh) - b(di - fg) + c(dh - eg) \] where \( a, b, c \) are the elements of the first row, and \( d, e, f, g, h, i \) are the elements of the second and third rows respectively. Substituting the values: \[ D = 0 \cdot (0 \cdot 0 - (-4) \cdot 4) - (-1) \cdot (-1 \cdot 0 - (-4)(-3)) + (-3) \cdot (-1 \cdot 4 - 0 \cdot (-3)) \] Calculating each term: 1. The first term is \( 0 \). 2. The second term is \( -1 \cdot (0 - 12) = 12 \). 3. The third term is \( -3 \cdot (-4) = 12 \). Thus, \[ D = 0 + 12 + 12 = 24 \] ### Step 3: Set the Equation Now we set the left-hand side equal to the right-hand side: \[ t = 24 \] ### Conclusion Thus, the value of \( t \) is: \[ \boxed{24} \]
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