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If |{:(x, 2, 3),(2,3,x),(3 , x,2):}| = |...

If `|{:(x, 2, 3),(2,3,x),(3 , x,2):}| = |{:(1, x, 4),(x,4,1),(4 , 1,x):}| = |{:(0, 5, x),(5,x,0),(x, 0,5):}|` = 0, then the value x equals (x `in` R )

A

0

B

5

C

`-5`

D

None of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( x \) such that the determinants of the given matrices are equal to zero. Let's denote the three determinants as \( D_1, D_2, \) and \( D_3 \). ### Step 1: Calculate \( D_1 \) The first determinant is: \[ D_1 = \begin{vmatrix} x & 2 & 3 \\ 2 & 3 & x \\ 3 & x & 2 \end{vmatrix} \] Using the determinant formula for a 3x3 matrix, we have: \[ D_1 = x \begin{vmatrix} 3 & x \\ x & 2 \end{vmatrix} - 2 \begin{vmatrix} 2 & x \\ 3 & 2 \end{vmatrix} + 3 \begin{vmatrix} 2 & 3 \\ 3 & x \end{vmatrix} \] Calculating each of the 2x2 determinants: 1. \( \begin{vmatrix} 3 & x \\ x & 2 \end{vmatrix} = 3 \cdot 2 - x \cdot x = 6 - x^2 \) 2. \( \begin{vmatrix} 2 & x \\ 3 & 2 \end{vmatrix} = 2 \cdot 2 - x \cdot 3 = 4 - 3x \) 3. \( \begin{vmatrix} 2 & 3 \\ 3 & x \end{vmatrix} = 2x - 9 \) Substituting back into the determinant: \[ D_1 = x(6 - x^2) - 2(4 - 3x) + 3(2x - 9) \] \[ = 6x - x^3 - 8 + 6x + 6x - 27 \] \[ = -x^3 + 18x - 35 \] ### Step 2: Calculate \( D_2 \) The second determinant is: \[ D_2 = \begin{vmatrix} 1 & x & 4 \\ x & 4 & 1 \\ 4 & 1 & x \end{vmatrix} \] Using the same determinant formula: \[ D_2 = 1 \begin{vmatrix} 4 & 1 \\ 1 & x \end{vmatrix} - x \begin{vmatrix} x & 1 \\ 4 & x \end{vmatrix} + 4 \begin{vmatrix} x & 4 \\ 4 & 1 \end{vmatrix} \] Calculating the 2x2 determinants: 1. \( \begin{vmatrix} 4 & 1 \\ 1 & x \end{vmatrix} = 4x - 1 \) 2. \( \begin{vmatrix} x & 1 \\ 4 & x \end{vmatrix} = x^2 - 4 \) 3. \( \begin{vmatrix} x & 4 \\ 4 & 1 \end{vmatrix} = x - 16 \) Substituting back: \[ D_2 = 1(4x - 1) - x(x^2 - 4) + 4(x - 16) \] \[ = 4x - 1 - (x^3 - 4x) + 4x - 64 \] \[ = -x^3 + 12x - 65 \] ### Step 3: Calculate \( D_3 \) The third determinant is: \[ D_3 = \begin{vmatrix} 0 & 5 & x \\ 5 & x & 0 \\ x & 0 & 5 \end{vmatrix} \] Using the determinant formula: \[ D_3 = 0 \cdot \begin{vmatrix} x & 0 \\ 0 & 5 \end{vmatrix} - 5 \cdot \begin{vmatrix} 5 & 0 \\ x & 5 \end{vmatrix} + x \cdot \begin{vmatrix} 5 & x \\ x & 0 \end{vmatrix} \] Calculating the 2x2 determinants: 1. \( \begin{vmatrix} 5 & 0 \\ x & 5 \end{vmatrix} = 25 \) 2. \( \begin{vmatrix} 5 & x \\ x & 0 \end{vmatrix} = -x^2 \) Substituting back: \[ D_3 = -5(25) + x(-x^2) = -125 - x^3 \] ### Step 4: Set the determinants equal to zero Since \( D_1 = D_2 = D_3 = 0 \), we can set up the equations: 1. \( -x^3 + 18x - 35 = 0 \) 2. \( -x^3 + 12x - 65 = 0 \) 3. \( -x^3 - 125 - x^3 = 0 \) ### Step 5: Solve the equations From \( D_1 = D_2 \): \[ - x^3 + 18x - 35 = - x^3 + 12x - 65 \] This simplifies to: \[ 6x = -30 \implies x = -5 \] Verifying with \( D_2 = D_3 \): \[ - x^3 + 12x - 65 = -125 - x^3 \] This simplifies to: \[ 12x - 65 = -125 \implies 12x = -60 \implies x = -5 \] ### Conclusion The value of \( x \) is: \[ \boxed{-5} \]
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