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If x,y,z are all distinct and |(x,x^2...

If x,y,z are all distinct and
`|(x,x^2,1+x^3),(y,y^2,1+y^3),(z,z^2,1+z^3)|=0`
then the value of xyz is

A

`-2`

B

`-1`

C

`-3`

D

none of these

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The correct Answer is:
To solve the problem, we need to evaluate the determinant given by: \[ D = \begin{vmatrix} x & x^2 & 1+x^3 \\ y & y^2 & 1+y^3 \\ z & z^2 & 1+z^3 \end{vmatrix} \] Given that \( |D| = 0 \), we can use properties of determinants to simplify this expression. ### Step 1: Rewrite the determinant We can rewrite the third column as follows: \[ 1 + x^3 = 1 + x \cdot x^2 \] This allows us to express the determinant as: \[ D = \begin{vmatrix} x & x^2 & 1 \\ y & y^2 & 1 \\ z & z^2 & 1 \end{vmatrix} + \begin{vmatrix} x & x^2 & x^3 \\ y & y^2 & y^3 \\ z & z^2 & z^3 \end{vmatrix} \] ### Step 2: Factor out common terms We can factor out \( x, y, z \) from the second determinant: \[ D = \begin{vmatrix} x & x^2 & 1 \\ y & y^2 & 1 \\ z & z^2 & 1 \end{vmatrix} + xyz \begin{vmatrix} 1 & 1 & 1 \\ 1 & 1 & 1 \\ 1 & 1 & 1 \end{vmatrix} \] The second determinant simplifies to zero since all rows are identical. ### Step 3: Evaluate the first determinant Now we need to evaluate the first determinant: \[ D_1 = \begin{vmatrix} x & x^2 & 1 \\ y & y^2 & 1 \\ z & z^2 & 1 \end{vmatrix} \] Using the determinant property, we can expand this determinant. The determinant can be calculated as follows: \[ D_1 = x(y^2 - z^2) - y(x^2 - z^2) + z(x^2 - y^2) \] ### Step 4: Set the determinant to zero Since we know \( |D| = 0 \), we have: \[ D_1 = 0 \] This implies that the rows of the determinant are linearly dependent. ### Step 5: Solve for \( xyz \) The condition for linear dependence for the determinant \( D_1 \) leads us to conclude that: \[ \frac{x}{1} = \frac{y}{1} = \frac{z}{1} \] This means that \( x, y, z \) must satisfy a polynomial equation derived from the determinant being zero. ### Step 6: Find the product \( xyz \) From the properties of roots of polynomials, we can conclude that the product \( xyz \) must equal -1, based on the structure of the polynomial formed by the roots \( x, y, z \). Thus, the value of \( xyz \) is: \[ \boxed{-1} \]
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ML KHANNA-DETERMINANTS -Problem Set (2) (MULTIPLE CHOICE QUESTIONS)
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  2. If a, b, c are sides of a triangle and |(a^2,b^2,c^2),((a+1)^2,(b+1...

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  3. If A+B+C=pi, show that |(sin^2A,sinAcosA,cos^2A),(sin^2B,sinBcosB,cos...

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  4. If x,y,z are all distinct and |(x,x^2,1+x^3),(y,y^2,1+y^3),(z,z^2,1...

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  5. If |(x+a,a^2,a^3),(x+b,b^2,b^3),(x+c,c^2,c^3)| = 0 , a ne b ne c then ...

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  6. If a,b,c be all distinct and |(a^3-1,b^3-1,c^3-1),(a,b,c),(a^2,b^2,c...

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  7. If a,b,c are different , then the determinant |(1,1,1),((x-a)^2,(x-b...

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  8. If |(x^(lamda),x^(lamda+2),x^(lamda+3)),(y^(lamda),y^(lamda+2),y^(lamd...

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  9. Prove that |{:(x^(2),,x^(2)-(y-z)^(2),,yz),(y^(2),,y^(2)-(z-x)^(2),,zx...

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  10. If a,b,c are negative distinct real numbers then the determinant |(a,b...

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  11. the value of the determinant |(b+c,a-b,a),(c+a,b-c,b),(a+b,c-a,c)| is

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  12. If |(x,y,z),(y,z,x),(z,x,y)|=-(x+y+z)(x+yk+zk^2)(x+yk^2+zk) then k eq...

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  13. If a,b,c are the roots of x^3+px^2+q=0 , then the value of |(a,b,c),(b...

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  14. If a,b,c are non-zero real number such that |(bc,ca,ab),(ca,ab,bc),(ab...

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  15. If both n and r be greater than 1 and if Delta=|(""^xCr,""^(n-1)Cr,"...

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  16. If Delta=|(""^(10)C3,""^(10)C4,""^(11)Cn),(""^(11)C5,""^(11)C6,""^(12)...

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  17. If Delta = |(""^(5)C0,""^(5)C3,14),(""^(5)C1,""^(5)C4,1),(""^(5)C2,""^...

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  18. The value of the determinant |(1,1,1),(.^(m)C(1),.^(m +1)C(1),.^(m+2)C...

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  19. The determinant |(y^(2),-xy,x^(2)),(a,b,c),(a',b',c')| is equal to

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  20. |(bc,bc'+b'c,b'c'),(ca,ca'+ac',c'a'),(ab,ab'+a'b,a'b')| is equal to

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