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Evaluate the following determinants by t...

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

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To evaluate the determinant \( D = \begin{vmatrix} 1 & 2 & 4 \\ -1 & 3 & 0 \\ 4 & 1 & 0 \end{vmatrix} \) using two methods, we will proceed as follows: ### Method 1: General Method (Cofactor Expansion) 1. **Identify the determinant**: \[ D = \begin{vmatrix} 1 & 2 & 4 \\ -1 & 3 & 0 \\ 4 & 1 & 0 \end{vmatrix} \] 2. **Use cofactor expansion along the first row**: \[ D = 1 \cdot D_{11} - 2 \cdot D_{12} + 4 \cdot D_{13} \] where \( D_{ij} \) is the determinant of the matrix obtained by removing the \( i \)-th row and \( j \)-th column. 3. **Calculate \( D_{11} \)**: \[ D_{11} = \begin{vmatrix} 3 & 0 \\ 1 & 0 \end{vmatrix} = (3 \cdot 0) - (0 \cdot 1) = 0 \] 4. **Calculate \( D_{12} \)**: \[ D_{12} = \begin{vmatrix} -1 & 0 \\ 4 & 0 \end{vmatrix} = (-1 \cdot 0) - (0 \cdot 4) = 0 \] 5. **Calculate \( D_{13} \)**: \[ D_{13} = \begin{vmatrix} -1 & 3 \\ 4 & 1 \end{vmatrix} = (-1 \cdot 1) - (3 \cdot 4) = -1 - 12 = -13 \] 6. **Substituting back into the determinant**: \[ D = 1 \cdot 0 - 2 \cdot 0 + 4 \cdot (-13) = 0 - 0 - 52 = -52 \] ### Method 2: Shortcut Method (Column Repetition) 1. **Write the determinant and repeat the first two columns**: \[ D = \begin{vmatrix} 1 & 2 & 4 \\ -1 & 3 & 0 \\ 4 & 1 & 0 \end{vmatrix} = \begin{vmatrix} 1 & 2 & 4 & 1 & 2 \\ -1 & 3 & 0 & -1 & 3 \\ 4 & 1 & 0 & 4 & 1 \end{vmatrix} \] 2. **Apply the formula**: \[ D = 1 \cdot (3 \cdot 0 - 0 \cdot 1) - 2 \cdot (-1 \cdot 0 - 4 \cdot 1) + 4 \cdot (-1 \cdot 1 - 3 \cdot 4) \] 3. **Calculate each term**: - First term: \( 1 \cdot 0 = 0 \) - Second term: \( -2 \cdot (-1 \cdot 0 - 4 \cdot 1) = -2 \cdot (-4) = 8 \) - Third term: \( 4 \cdot (-1 - 12) = 4 \cdot (-13) = -52 \) 4. **Combine the results**: \[ D = 0 + 8 - 52 = -52 \] ### Final Result Thus, the value of the determinant is: \[ \boxed{-52} \]
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MODERN PUBLICATION-DETERMINANTS-Exercise 4(a) (SHORT ANSWER TYPE QUESTIONS)
  1. Evalute the determinants in queations 1 and 2 : Find the values of x...

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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