Home
Class 12
MATHS
Evaluate the following determinants by t...

Evaluate the following determinants by two method :
`|{:(0,2,0),(2,3,4),(4,5,6):}|`

Text Solution

AI Generated Solution

The correct Answer is:
To evaluate the determinant \( | \begin{pmatrix} 0 & 2 & 0 \\ 2 & 3 & 4 \\ 4 & 5 & 6 \end{pmatrix} | \) using two methods, we will follow these steps: ### Method 1: General Method 1. **Write the determinant**: \[ D = \begin{vmatrix} 0 & 2 & 0 \\ 2 & 3 & 4 \\ 4 & 5 & 6 \end{vmatrix} \] 2. **Expand the determinant using the first row**: \[ D = 0 \cdot \text{Cofactor}(1,1) + 2 \cdot \text{Cofactor}(1,2) + 0 \cdot \text{Cofactor}(1,3) \] Since the first and third terms are multiplied by 0, we only need to calculate the second term: \[ D = 2 \cdot \text{Cofactor}(1,2) \] 3. **Calculate the Cofactor(1,2)**: The cofactor is calculated as: \[ \text{Cofactor}(1,2) = (-1)^{1+2} \cdot \begin{vmatrix} 2 & 4 \\ 4 & 6 \end{vmatrix} \] Calculate the 2x2 determinant: \[ \begin{vmatrix} 2 & 4 \\ 4 & 6 \end{vmatrix} = (2 \cdot 6) - (4 \cdot 4) = 12 - 16 = -4 \] Thus, \[ \text{Cofactor}(1,2) = -(-4) = 4 \] 4. **Substitute back into the determinant**: \[ D = 2 \cdot 4 = 8 \] ### Method 2: Shortcut Method 1. **Write the determinant**: \[ D = \begin{vmatrix} 0 & 2 & 0 \\ 2 & 3 & 4 \\ 4 & 5 & 6 \end{vmatrix} \] 2. **Use the shortcut method**: - Write down the elements of the determinant: - \( a_1 = 0, a_2 = 2, a_3 = 0 \) - \( b_1 = 2, b_2 = 3, b_3 = 4 \) - \( c_1 = 4, c_2 = 5, c_3 = 6 \) 3. **Calculate using the formula**: \[ D = a_1b_2c_3 + a_2b_3c_1 + a_3b_1c_2 - (a_3b_2c_1 + a_2b_1c_3 + a_1b_3c_2) \] Substituting the values: \[ D = 0 \cdot 3 \cdot 6 + 2 \cdot 4 \cdot 4 + 0 \cdot 2 \cdot 5 - (0 \cdot 3 \cdot 4 + 2 \cdot 2 \cdot 6 + 0 \cdot 4 \cdot 5) \] Simplifying: \[ D = 0 + 32 + 0 - (0 + 24 + 0) = 32 - 24 = 8 \] ### Final Result Thus, the value of the determinant is: \[ \boxed{8} \]
Promotional Banner

Topper's Solved these Questions

  • DETERMINANTS

    MODERN PUBLICATION|Exercise Exercise 4(b) (SHORT ANSWER TYPE QUESTIONS)|11 Videos
  • DETERMINANTS

    MODERN PUBLICATION|Exercise Exercise 4(b) (LONG ANSWER TYPE QUESTIONS (I))|19 Videos
  • DETERMINANTS

    MODERN PUBLICATION|Exercise Examples (QUESTIONS FROM NCERT EXAMPLAR|4 Videos
  • CONTINUITY AND DIFFERENTIABILITY

    MODERN PUBLICATION|Exercise CHAPTER TEST|12 Videos
  • DIFFERENTIAL EQUATIONS

    MODERN PUBLICATION|Exercise CHAPTER TEST (9)|12 Videos

Similar Questions

Explore conceptually related problems

Evaluate the following determinants by two method : |{:(1,2,4),(-1,3,0),(4,1,0):}|

Find the values of the following determinants |{:(4,0,2),(1,5,-6),(3,-2,8):}|

Find the values of the following determinants |{:(12,-10,5),(3,2,-1),(-4,0,3):}|

Find the inverses of the following matrices by adjoint method : (1) {:((1,2),(2,3)):}" "(2){:((5,4),(3,2)):}" "(3){:((3,-2),(6,8)):}" "(4){:((2,-3),(3,5)):} .

Find out arithmetic mean from the following distribution by Short-cut Method: {:("Items",10-8,8-6,6-4,4-2,2-0),("Frequency"," "10," "8," "6," "4," "2):}

If lambda "and" mu are the cofactors of 3 and -2 respectively in the determinant |{:(1,0,-2),(3,-1,2),(4,5,6):}| the value of lambda+mu is

Find the determinant of a matrix [{:(2,-3),(4," "5):}]

Find minor and cofactors or all the elements of determinant |{:(-1,2,3),(-4,5,-2),(6,4,8):}|

MODERN PUBLICATION-DETERMINANTS-Exercise 4(a) (SHORT ANSWER TYPE QUESTIONS)
  1. Evalute the determinants in queations 1 and 2 : Find the values of x...

    Text Solution

    |

  2. Evalute the determinants in queations 1 and 2 : Find the values of x...

    Text Solution

    |

  3. Solve the equation: |[3,x],[x,1]|=|[3,2],[4,1]|

    Text Solution

    |

  4. Find the value of 'x' if : |{:(3,x),(x,1):}|=|{:(5,2),(4,-1):}|

    Text Solution

    |

  5. Find the value of 'x' if : |{:(2x,3),(5,2):}|=|{:(16,3),(5,2):}|, x ...

    Text Solution

    |

  6. if |(x+1,x-1),(x-3,x+2)|= |(4,-1),(1,3)|. find the value of x.

    Text Solution

    |

  7. Find the value of 'x' if : |{:(-1,2),(4,8):}|=|{:(2,x),(x,-4):}|

    Text Solution

    |

  8. If |xx1x|=|3 4 1 2|, write the positive value of xdot

    Text Solution

    |

  9. If A=[{:(1,3),(4,1):}], then find |3A'|.

    Text Solution

    |

  10. |[3,-1,-2],[ 0, 0,-1],[ 3,-5, 0]|

    Text Solution

    |

  11. Write the minor and cofactor of each element of second column in the f...

    Text Solution

    |

  12. Evalute the determinants : (i) |{:(3,-1,-2),(0,0,1),(3,-5,0):}| (i...

    Text Solution

    |

  13. Evalute the determinants : (i) |{:(3,-1,-2),(0,0,1),(3,-5,0):}| (i...

    Text Solution

    |

  14. Evaluate the following determinants : |{:(3,-4,5),(1,1,-2),(2,3,1):}...

    Text Solution

    |

  15. Evaluate the following determinants by two method : |{:(1,2,4),(-1,3...

    Text Solution

    |

  16. Evaluate the following determinants by two method : |{:(0,2,0),(2,3,...

    Text Solution

    |

  17. Evalute the determinants in queations 1 and 2 : If A = |{:(1,1,-2),(...

    Text Solution

    |

  18. If A=[{:(2,1,1),(1,2,1),(1,1,2):}], then show that : |4A|=64|A|.

    Text Solution

    |

  19. |(1!,2!,3!),(2!,3!,4!),(3!,4!,5!)|=?

    Text Solution

    |

  20. If |{:(x+1,1,1),(1,x+1,1),(-1,1,x+1):}|=0, find the value of 'x'.

    Text Solution

    |