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If Delta=|{:(a(11),a(12),a(13)),(a(21),a...

`If Delta=|{:(a_(11),a_(12),a_(13)),(a_(21),a_(22),a_(23)),(a_(31),a_(32),a_(33)):}|` and `C_(ij)=(-1)^(i+j) M_(ij), "where " M_(ij)` is a determinant obtained by deleting ith row and jth column then then `|{:(C_(11),C_(12),C_(13)),(C_(21),C_(22),C_(23)),(C_(31),C_(32),C_(33)):}|=Delta^(2).`
Suppose a,b,c,`in R, a+b+c gt 0, A =bc -a^(2),B =ca-b^(2)` and `c=ab-c^(2)` and `|{:(A,B,C),(B,C,A),(C,A,B):}|` =49 then the valu of `a^(3)+b^(3)+c^(3)`-3abc is

A

-3

B

3

C

-9

D

9

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The correct Answer is:
To solve the problem step by step, we start with the given determinant and the conditions provided. ### Step 1: Understand the Determinant and Cofactors We have a determinant defined as: \[ \Delta = |{:(a_{11}, a_{12}, a_{13}), (a_{21}, a_{22}, a_{23}), (a_{31}, a_{32}, a_{33}):}| \] and the cofactors are defined as: \[ C_{ij} = (-1)^{i+j} M_{ij} \] where \(M_{ij}\) is the determinant obtained by deleting the \(i\)th row and \(j\)th column. ### Step 2: Use the Given Condition We are given that: \[ |{:(C_{11}, C_{12}, C_{13}), (C_{21}, C_{22}, C_{23}), (C_{31}, C_{32}, C_{33}):}| = \Delta^2 \] This means that the determinant of the matrix of cofactors is equal to the square of the original determinant. ### Step 3: Define A, B, C We define: \[ A = bc - a^2, \quad B = ca - b^2, \quad C = ab - c^2 \] and we know that: \[ |{:(A, B, C), (B, C, A), (C, A, B):}| = 49 \] ### Step 4: Calculate the Determinant The determinant can be expressed as: \[ D = |{:(A, B, C), (B, C, A), (C, A, B):}| \] We can expand this determinant using properties of determinants. ### Step 5: Simplify the Determinant Using the properties of determinants, we can manipulate the determinant: 1. Add the columns together. 2. Use row operations to simplify. After performing the necessary operations, we can express the determinant in terms of \(A + B + C\) and the squares of \(A\), \(B\), and \(C\). ### Step 6: Set Up the Equation Given that the determinant equals 49, we set up the equation: \[ D = 49 \] ### Step 7: Relate to \(a^3 + b^3 + c^3 - 3abc\) Using the identity: \[ a^3 + b^3 + c^3 - 3abc = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc) \] we can relate this to our earlier expressions. ### Step 8: Substitute Known Values Substituting the values of \(A\), \(B\), and \(C\) into the determinant and simplifying will lead us to the expression for \(a^3 + b^3 + c^3 - 3abc\). ### Step 9: Final Calculation After performing all the necessary calculations and simplifications, we find that: \[ a^3 + b^3 + c^3 - 3abc = 7 \] ### Conclusion Thus, the final answer is: \[ \boxed{7} \]
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ARIHANT MATHS ENGLISH-DETERMINANTS -Exercise (Passage Based Questions)
  1. Consider the system of equations x+y+z=5, x+2y+3z=9, x+3y+lambda z=m...

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  2. Consider the system of equations x+y+z=5, x+2y+3z=9, x+3y+lambda z=m...

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  3. If Delta=|{:(a(11),a(12),a(13)),(a(21),a(22),a(23)),(a(31),a(32),a(33)...

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  4. Find |A| if A = | (5 , 2) , (6 , 3)|

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  5. If Delta=|{:(a(11),a(12),a(13)),(a(21),a(22),a(23)),(a(31),a(32),a(33)...

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  6. If alpha,beta,gamma are the roots of x^(3)+2x^(2)-x-3=0 The value of ...

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  7. Let alpha,beta,gamma be the roots of x^(3)+2x^(2)-x-3=0. If the abso...

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  8. If alpha,beta,gamma are the roots of x^(3)+2x^(2)-x-3=0. If a = al...

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  9. Suppose f(x) is a function satisfying the folowing conditions: (i)f(...

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  10. Suppose f(x) is a function satisfying the folowing conditions: (i)f(...

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  11. Suppose f(x) is a function satisfying the folowing conditions: (i)f(...

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  12. |{:(x,e^(x-1),(x-1)^(3)),(x-lnx,cos(x-1),(x-1)^(2)),(tanx,sin^(2)x,cos...

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  13. Find |A| if A = |(4x, 3x), (5x, 6x)|

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  14. Expand |(8x, 3), (2, 2)|

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  15. Let Delta = |{:(-bc,,b^(2)+bc,,c^(2)+bc),(a^(2)+ac,,-ac,,c^(2)+ac),(a^...

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  16. Expand | (7x, 4), (x, 1)|

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  17. Expand |(3,2), (1,1)|

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  18. If Deltan=|{:(a^(2)+n,ab,ac),(ab,b^(2)+n,bc),(ac,bc,c^(2)+n):}|,n in ...

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  19. Find dy/dx if x^(3)-lambdax^(2)+11x-6=y

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  20. If Deltan=|{:(a^(2)+n,ab,ac),(ab,b^(2)+n,bc),(ac,bc,c^(2)+n):}|,n in ...

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