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The value of |(i^m,i^(m+1),i^(m+2)),(i^...

The value of `|(i^m,i^(m+1),i^(m+2)),(i^(m+5),i^(m+4),i^(m+3)),(i^(m+6),i^(m+7),i^(m+8))|` , when `i=sqrt-1`, is

A

1 if m is a multiple of 4

B

0 for all real m

C

`-1` if m is a multiple of 3

D

2

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The correct Answer is:
To solve the determinant \( D = \begin{vmatrix} i^m & i^{m+1} & i^{m+2} \\ i^{m+5} & i^{m+4} & i^{m+3} \\ i^{m+6} & i^{m+7} & i^{m+8} \end{vmatrix} \), where \( i = \sqrt{-1} \), we can follow these steps: ### Step 1: Write the Determinant We start with the determinant: \[ D = \begin{vmatrix} i^m & i^{m+1} & i^{m+2} \\ i^{m+5} & i^{m+4} & i^{m+3} \\ i^{m+6} & i^{m+7} & i^{m+8} \end{vmatrix} \] ### Step 2: Expand the Determinant We will expand the determinant using the first row: \[ D = i^m \begin{vmatrix} i^{m+4} & i^{m+3} \\ i^{m+7} & i^{m+8} \end{vmatrix} - i^{m+1} \begin{vmatrix} i^{m+5} & i^{m+3} \\ i^{m+6} & i^{m+8} \end{vmatrix} + i^{m+2} \begin{vmatrix} i^{m+5} & i^{m+4} \\ i^{m+6} & i^{m+7} \end{vmatrix} \] ### Step 3: Calculate the 2x2 Determinants Now we calculate the 2x2 determinants: 1. For the first determinant: \[ \begin{vmatrix} i^{m+4} & i^{m+3} \\ i^{m+7} & i^{m+8} \end{vmatrix} = i^{m+4} \cdot i^{m+8} - i^{m+3} \cdot i^{m+7} = i^{2m+12} - i^{2m+10} = i^{2m+10}(i^2 - 1) = i^{2m+10}(-1) = -i^{2m+10} \] 2. For the second determinant: \[ \begin{vmatrix} i^{m+5} & i^{m+3} \\ i^{m+6} & i^{m+8} \end{vmatrix} = i^{m+5} \cdot i^{m+8} - i^{m+3} \cdot i^{m+6} = i^{2m+13} - i^{2m+9} = i^{2m+9}(i^4 - 1) = i^{2m+9}(0) = 0 \] 3. For the third determinant: \[ \begin{vmatrix} i^{m+5} & i^{m+4} \\ i^{m+6} & i^{m+7} \end{vmatrix} = i^{m+5} \cdot i^{m+7} - i^{m+4} \cdot i^{m+6} = i^{2m+12} - i^{2m+10} = i^{2m+10}(i^2 - 1) = -i^{2m+10} \] ### Step 4: Substitute Back into the Determinant Substituting these back into the expression for \( D \): \[ D = i^m (-(-i^{2m+10})) - i^{m+1}(0) + i^{m+2}(-i^{2m+10}) \] \[ D = i^m i^{2m+10} + 0 - i^{m+2} i^{2m+10} = i^{3m+10} - i^{3m+10} = 0 \] ### Conclusion Thus, the value of the determinant is: \[ \boxed{0} \]
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AAKASH INSTITUTE ENGLISH-DETERMINANTS -SECTION - B
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  18. If |{:(,x^(k),x^(k+2),x^(k+3)),(,y^(k),y^(k+2),y^(k+3)),(,z^(k),z^(k+2...

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  19. If all elements of a third order determinant are equal to 1 or -1. the...

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  20. If A is a 3xx3 matrix and det (3A) = k det(A) , k is equal to:

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