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If w is a complex cube root of unity, th...

If w is a complex cube root of unity, then the value of the determinant
`Delta = [(1,w,w^(2)),(w,w^(2),1),(w^(2),1,w)]`, is

A

1

B

0

C

`w^(2)`

D

w

Text Solution

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The correct Answer is:
To find the value of the determinant \[ \Delta = \begin{vmatrix} 1 & w & w^2 \\ w & w^2 & 1 \\ w^2 & 1 & w \end{vmatrix} \] where \( w \) is a complex cube root of unity, we can follow these steps: ### Step 1: Understand the properties of cube roots of unity The complex cube roots of unity are \( 1, w, w^2 \) where \( w = e^{2\pi i / 3} \) and satisfies the equation \( w^3 = 1 \). This also implies that: \[ 1 + w + w^2 = 0 \] ### Step 2: Apply a column operation We can simplify the determinant by applying a column operation. We will add all three columns together to the first column: \[ C_1 \rightarrow C_1 + C_2 + C_3 \] This gives us: \[ C_1 = 1 + w + w^2 = 0 \] So, the first column becomes: \[ C_1 = \begin{pmatrix} 0 \\ 0 \\ 0 \end{pmatrix} \] ### Step 3: Write the new determinant After performing the column operation, the determinant now looks like: \[ \Delta = \begin{vmatrix} 0 & w & w^2 \\ 0 & w^2 & 1 \\ 0 & 1 & w \end{vmatrix} \] ### Step 4: Evaluate the determinant Since the first column is entirely zeros, the value of the determinant is: \[ \Delta = 0 \] ### Conclusion Thus, the value of the determinant \( \Delta \) is: \[ \Delta = 0 \]

To find the value of the determinant \[ \Delta = \begin{vmatrix} 1 & w & w^2 \\ w & w^2 & 1 \\ w^2 & 1 & w \end{vmatrix} ...
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