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If omega is a cube root of unity, then ...

If `omega` is a cube root of unity, then a root of the following equation is
`|(x+1,omega,omega^2),(omega,x+omega^2,1),(omega^2,1,x+omega)|` = 0

A

x = 1

B

`x=omega`

C

`x=omega^2`

D

x = 0

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the root of the determinant equation given by: \[ \left| \begin{array}{ccc} x+1 & \omega & \omega^2 \\ \omega & x+\omega^2 & 1 \\ \omega^2 & 1 & x+\omega \end{array} \right| = 0 \] Where \(\omega\) is a cube root of unity. The cube roots of unity satisfy the equation \(1 + \omega + \omega^2 = 0\). ### Step 1: Apply Row Operations We can simplify the determinant by applying row operations. Specifically, we will add the second and third rows to the first row. \[ R_1 \rightarrow R_1 + R_2 + R_3 \] This gives us: \[ R_1 = (x + 1 + \omega + \omega^2, \omega + (x + \omega^2) + 1, \omega^2 + 1 + (x + \omega)) \] Using the property of cube roots of unity, we know that \(\omega + \omega^2 = -1\). Thus: - For the first element of \(R_1\): \[ x + 1 + \omega + \omega^2 = x + 1 - 1 = x \] - For the second element of \(R_1\): \[ \omega + (x + \omega^2) + 1 = \omega + x - 1 + 1 = x + \omega \] - For the third element of \(R_1\): \[ \omega^2 + 1 + (x + \omega) = \omega^2 + 1 + x - 1 = x + \omega^2 \] So the new determinant becomes: \[ \left| \begin{array}{ccc} x & x + \omega & x + \omega^2 \\ \omega & x + \omega^2 & 1 \\ \omega^2 & 1 & x + \omega \end{array} \right| = 0 \] ### Step 2: Factor Out \(x\) Now, we can factor \(x\) out of the first row: \[ = x \left| \begin{array}{ccc} 1 & 1 + \frac{\omega}{x} & 1 + \frac{\omega^2}{x} \\ \omega & x + \omega^2 & 1 \\ \omega^2 & 1 & x + \omega \end{array} \right| = 0 \] This gives us two cases to consider: 1. \(x = 0\) 2. The determinant must equal zero. ### Step 3: Solve the Determinant Now we need to solve the determinant: \[ \left| \begin{array}{ccc} 1 & 1 + \frac{\omega}{x} & 1 + \frac{\omega^2}{x} \\ \omega & x + \omega^2 & 1 \\ \omega^2 & 1 & x + \omega \end{array} \right| = 0 \] However, since we are only interested in finding a single root, we can conclude that one root is: \[ x = 0 \] ### Conclusion Thus, the root of the equation is: \[ \boxed{0} \]
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