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The value of the determinant : |(1-alpha...

The value of the determinant : `|(1-alpha,alpha-alpha^(2),alpha^(2)),(1-beta,beta-beta^(2),beta^(2)),(1-gamma,gamma-gamma^(2),gamma^(2))|` is equal to :

A

A) `(alpha - beta) (beta - gamma) (alpha - gamma)`

B

B) `(alpha - beta) (beta - gamma) (gamma - alpha)`

C

C) `(alpha - beta) (beta - gamma) (gamma - alpha) (alpha + beta + gamma)`

D

D) 0

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To find the value of the determinant \[ D = \begin{vmatrix} 1 - \alpha & \alpha - \alpha^2 & \alpha^2 \\ 1 - \beta & \beta - \beta^2 & \beta^2 \\ 1 - \gamma & \gamma - \gamma^2 & \gamma^2 \end{vmatrix} \] we will perform a series of column and row operations. ### Step 1: Column Operations We will first perform the column operation \( C_1 \leftarrow C_1 + C_2 + C_3 \) to simplify the first column. \[ C_1 = (1 - \alpha) + (\alpha - \alpha^2) + \alpha^2 = 1 \] So, the first column becomes: \[ C_1 = \begin{pmatrix} 1 \\ 1 \\ 1 \end{pmatrix} \] The determinant now looks like this: \[ D = \begin{vmatrix} 1 & \alpha - \alpha^2 & \alpha^2 \\ 1 & \beta - \beta^2 & \beta^2 \\ 1 & \gamma - \gamma^2 & \gamma^2 \end{vmatrix} \] ### Step 2: Further Column Operations Next, we apply the operation \( C_2 \leftarrow C_2 + C_3 \): \[ C_2 = (\alpha - \alpha^2) + \alpha^2 = \alpha \] \[ C_2 = (\beta - \beta^2) + \beta^2 = \beta \] \[ C_2 = (\gamma - \gamma^2) + \gamma^2 = \gamma \] Now, the determinant becomes: \[ D = \begin{vmatrix} 1 & \alpha & \alpha^2 \\ 1 & \beta & \beta^2 \\ 1 & \gamma & \gamma^2 \end{vmatrix} \] ### Step 3: Row Operations Now we will perform row operations. We will subtract the first row from the second and third rows: \[ R_2 \leftarrow R_2 - R_1 \quad \text{and} \quad R_3 \leftarrow R_3 - R_1 \] This gives us: \[ D = \begin{vmatrix} 1 & \alpha & \alpha^2 \\ 0 & \beta - \alpha & \beta^2 - \alpha^2 \\ 0 & \gamma - \alpha & \gamma^2 - \alpha^2 \end{vmatrix} \] ### Step 4: Expanding the Determinant Now we can expand the determinant along the first column: \[ D = 1 \cdot \begin{vmatrix} \beta - \alpha & \beta^2 - \alpha^2 \\ \gamma - \alpha & \gamma^2 - \alpha^2 \end{vmatrix} \] ### Step 5: Simplifying the 2x2 Determinant Now, we compute the 2x2 determinant: \[ D = (\beta - \alpha)((\gamma^2 - \alpha^2)) - (\gamma - \alpha)(\beta^2 - \alpha^2) \] Using the identity \( a^2 - b^2 = (a-b)(a+b) \): \[ D = (\beta - \alpha)(\gamma - \alpha)(\gamma + \alpha) - (\gamma - \alpha)(\beta - \alpha)(\beta + \alpha) \] ### Step 6: Factoring Out Common Terms We can factor out \( (\beta - \alpha)(\gamma - \alpha) \): \[ D = (\beta - \alpha)(\gamma - \alpha) \left( (\gamma + \alpha) - (\beta + \alpha) \right) \] \[ D = (\beta - \alpha)(\gamma - \alpha)(\gamma - \beta) \] ### Final Result Thus, the value of the determinant is: \[ D = (\alpha - \beta)(\beta - \gamma)(\gamma - \alpha) \]
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PUNEET DOGRA-DETERMINANTS -PREV YEAR QUESTIONS
  1. The system of equation kx + y + z = 1, x + ky + z = k and x + y + kz =...

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  2. If p + q + r = a + b + c = 0, then the determinant |(pa,qb,rc),(qc,ra,...

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  3. The value of the determinant : |(1-alpha,alpha-alpha^(2),alpha^(2)),(1...

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  4. If B is a non-singular matrix and A is a square matrix, then the value...

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  5. What is the value of the determinant ? |(1,1,1),(1,1+xyz,1),(1,1,1+x...

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  6. If |(x,y,0),(0,x,y),(y,0,x)| = 0, then which one of the following is c...

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  7. If A=[(cos alpha,sin alpha),(-sin alpha,cos alpha)] and A. adj A=[(k,...

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  8. If a ne b ne c, then one value of x which satisfies the equation. [(0,...

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  9. Let ax^(3) + bx^(2) + cx + d |(x+1,2x,3x),(2x+3,x+1,x),(2-x,3x+4,5x-...

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  10. Let ax^(3) + bx^(2) + cx + d |(x+1,2x,3x),(2x+3,x+1,x),(2-x,3x+4,5x-...

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  11. If A is a square matrix of order 3 and det A = 5, then what is det [(2...

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  12. Which of the following determinants have value 'zero' ? 1. |(41,1,5)...

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  13. If the value of the determinant |(a,1,1),(1,b,1),(1,1,c)| is positive,...

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  14. Consider the following statements in respect of the determinant |("cos...

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  15. If a, b and c are real numbers, then the value of the determinant |(1-...

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  16. Consider the following statements with respect to the square matrices ...

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  17. The value of |(1,1,1),(1,1+x,1),(1,1,1+y)| is

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  18. Consider the following statements I. Determinant is a square matrix....

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  19. If |(a,b,0),(0,a,b),(b,0,a)| = 0, then which one of the following is c...

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  20. If a ne b ne c all are positive, then the value of determinant |(a,b,c...

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