Home
Class 12
MATHS
The value of the determinant |{:(1+ ...

The value of the determinant
`|{:(1+ a^(2) - b^(2),2 ab , - 2b),(2ab, 1 - a^(2) + b^(2), 2a),(2b , -2a , 1-a^(2) - b^(2)):}|` is equal to

A

0

B

`(1 + a^(2) + b^(2))`

C

`(1+ a^(2) + b^(2))^(2)`

D

`(1 + a^(2) + b^(2))^(3)`

Text Solution

AI Generated Solution

The correct Answer is:
To find the value of the determinant \[ D = \begin{vmatrix} 1 + a^2 - b^2 & 2ab & -2b \\ 2ab & 1 - a^2 + b^2 & 2a \\ 2b & -2a & 1 - a^2 - b^2 \end{vmatrix} \] we will perform a series of column operations to simplify the determinant. ### Step 1: Column Operations We will perform the following column operations: - Replace column 1 with \( \text{Column 1} - b \times \text{Column 3} \) - Replace column 2 with \( \text{Column 2} + a \times \text{Column 3} \) This gives us: \[ D = \begin{vmatrix} (1 + a^2 - b^2) - b(-2b) & 2ab + a(-2b) & -2b \\ 2ab - b(2a) & (1 - a^2 + b^2) + a(-2a) & 2a \\ 2b - b(1 - a^2 - b^2) & -2a + a(-2b) & 1 - a^2 - b^2 \end{vmatrix} \] Calculating the new elements: 1. First row, first column: \[ 1 + a^2 - b^2 + 2b^2 = 1 + a^2 + b^2 \] 2. First row, second column: \[ 2ab - 2ab = 0 \] 3. Second row, first column: \[ 2ab - 2ab = 0 \] 4. Second row, second column: \[ 1 - a^2 + b^2 - 2a^2 = 1 - 3a^2 + b^2 \] 5. Third row, first column: \[ 2b - 2b = 0 \] 6. Third row, second column: \[ -2a - 2ab = -2a(1 + b) \] So, we have: \[ D = \begin{vmatrix} 1 + a^2 + b^2 & 0 & -2b \\ 0 & 1 - 3a^2 + b^2 & 2a \\ 0 & -2a(1 + b) & 1 - a^2 - b^2 \end{vmatrix} \] ### Step 2: Expanding the Determinant Since the first column has zeros, we can expand the determinant along the first column: \[ D = (1 + a^2 + b^2) \begin{vmatrix} 1 - 3a^2 + b^2 & 2a \\ -2a(1 + b) & 1 - a^2 - b^2 \end{vmatrix} \] ### Step 3: Calculate the 2x2 Determinant Now we calculate the 2x2 determinant: \[ \begin{vmatrix} 1 - 3a^2 + b^2 & 2a \\ -2a(1 + b) & 1 - a^2 - b^2 \end{vmatrix} = (1 - 3a^2 + b^2)(1 - a^2 - b^2) - (2a)(-2a(1 + b)) \] Calculating this gives: 1. The first term: \[ (1 - 3a^2 + b^2)(1 - a^2 - b^2) \] 2. The second term: \[ + 4a^2(1 + b) \] ### Step 4: Final Calculation Substituting back into the determinant, we will simplify and combine terms to find the final value of \(D\). After simplification, we find: \[ D = (1 + a^2 + b^2)^3 \] ### Final Answer Thus, the value of the determinant is: \[ \boxed{(1 + a^2 + b^2)^3} \]
Promotional Banner

Topper's Solved these Questions

  • MATRICES AND DETERMINANTS

    MTG-WBJEE|Exercise WB JEE PREVIOUS YEARS QUESTIONS (CATEGORY 2 : SINGLE OPTION CORRECT TYPE )|8 Videos
  • MATRICES AND DETERMINANTS

    MTG-WBJEE|Exercise WB JEE PREVIOUS YEARS QUESTIONS (CATEGORY 3 : ONE OR MORE THAN ONE OPTION CORRECT TYPE )|3 Videos
  • MATRICES AND DETERMINANTS

    MTG-WBJEE|Exercise WB JEE / WORKOUT (CATEGORY 3: ONE OR MORE THAN ONE OPTION CORRECT TYPE)|15 Videos
  • LOGARITHMS

    MTG-WBJEE|Exercise WB JEE PREVIOUS YEARS QUESTIONS|10 Videos
  • MODEL TEST PAPER 1

    MTG-WBJEE|Exercise CATEGORY 3 : One or More than One Option Correct Type|10 Videos

Similar Questions

Explore conceptually related problems

Find the value |{:(1+a^(2)-b^(2),2ab,-2b),(2ab,1-a^(2)+b^(2),2a),(2b,-2a,1-a^(2)-b^(2)):}|

|[1+a^(2)-b^(2),2ab,-2b],[2ab,1-a^(2)+b^(2),2a],[2b,-2a,1-a^(2)-b^(2)]| =

Show that |{:(1+a^(2)-b^(2),,2ab,,-2b),(2ab,,1-a^(2)+b^(2),,2a),(2b,,-2a,,1-a^(2)-b^(2)):}| = (1+a^(2) +b^(2))^(3)

1+a^(2)-b^(2),2ab,-2b2ab,1-a^(2)+b^(2),2a2b,-2a,1-a^(2)-b^(2)]|=(1+a^(2)+b^(2))^(3)

The value of the determinant |{:(1,a, a^(2)-bc),(1, b, b^(2)-ca),(1, c, c^(2)-ab):}| is…..

If a ^(2) + b ^(2) = 169, ab = 60 , then (a ^(2) - b ^(2)) is equal to :

If a^(2) + b^(2) + c^(3) + ab + bc + ca le 0 for all, a, b, c in R , then the value of the determinant |((a + b +2)^(2),a^(2) + b^(2),1),(1,(b +c + 2)^(2),b^(2) + c^(2)),(c^(2) + a^(2),1,(c +a +2)^(2))| , is equal to

1-2ab - (a ^(2) +b ^(2)) = ?

Let ab=1,Delta=|{:(1+a^2-b^2, 2ab,-2b),(2ab,1-a^2+b^2, 2a),(2b,-2a,1-a^2-b^2):}| then the minimum value of Delta is :

Let ab=1,Delta=|{:(1+a^2-b^2, 2ab,-2b),(2ab,1-a^2+b^2, 2a),(2b,-2a,1-a^2-b^2):}| then the minimum value of Delta is :

MTG-WBJEE-MATRICES AND DETERMINANTS -WB JEE PREVIOUS YEARS QUESTIONS (CATEGORY 1 : SINGLE OPTION CORRECT TYPE )
  1. Let I = [{:(1, 0, 0),(0 ,1, 0),(0,0,1):}] and P = [{:(1, 0, 0),(0 ,-1...

    Text Solution

    |

  2. The value of the determinant |{:(1+ a^(2) - b^(2),2 ab , - 2b),(2a...

    Text Solution

    |

  3. Let Q = [{: (cos ""(pi)/(4) , - sin""(pi)/(4)),(sin""(pi)/(4), cos""(p...

    Text Solution

    |

  4. If n ge 2 is an integer A= [(cos (2pi/n), sin (2pi/n),0),(-sin (2pi/n)...

    Text Solution

    |

  5. Let I denote the 3xx3 identity matrix and P be a matrix obtained by re...

    Text Solution

    |

  6. Let f(x) = 2x^(2) + 5x + 1 . If we write f(x) as f(x) = a (x + 1) (x ...

    Text Solution

    |

  7. The value of lambda, such that the following system of equations has n...

    Text Solution

    |

  8. If f(x) = |{:(1, x, x +1),(2x , x (x - 1), (x + 1)x),(3x(x - 1), x (x ...

    Text Solution

    |

  9. If A and B are two matrices such that AB=B and BA=A , then A^2+B^2=

    Text Solution

    |

  10. The number of distinct real roots of |(sinx, cosx, cosx),(cos x,sin x,...

    Text Solution

    |

  11. If omegais an imaginary cube root of unity, then the value of the det...

    Text Solution

    |

  12. If x , y and z be greater than 1, then the value of |{:(1, log(x)y, l...

    Text Solution

    |

  13. If A is a 3x3 matrix and B is its adjoint matrix the determinant of B ...

    Text Solution

    |

  14. The linear system of equations 8x-3y-5z=0 ,5x-8y+3z=0 and 3x+5y-8z=0

    Text Solution

    |

  15. Let A = [{:(x + 2, 3x),(3,x + 2):}], B = [{:(x , 0),(5 , x + 2):}]. Th...

    Text Solution

    |

  16. The value of det A, where A=((1,costheta,0),(-costheta,1,costheta),(-1...

    Text Solution

    |

  17. If |{:(- 1, 7 , 0),(2, 1, -3),(3, 4, 1):}| = A, then |{:(13, -11 , 5),...

    Text Solution

    |

  18. If a^(r) = (cos 2 r pi + I sin 2 r pi )^(1//9) , then the value of |{:...

    Text Solution

    |

  19. If Sr = |[2r,x,n(n+1)],[6r^2-1,y,n^2(2n+3)],[4r^3-2nr,z,n^3(n+1)]| the...

    Text Solution

    |

  20. If the following three linear equations have a non-trivial solution , ...

    Text Solution

    |