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Let $\alpha = \frac{-1 + i\sqrt{3}}{2}$ and $\beta = \frac{-1 - i\sqrt{3}}{2}$, $i = \sqrt{-1}$. If $(7 - 7\alpha + 9\beta)^{20} + (9 + 7\alpha - 7\beta)^{20} + (-7 + 9\alpha + 7\beta)^{20} + (14 + 7\alpha + 7\beta)^{20} = m^{10}$, then $m$ is _________

First, recognize that $\alpha$ and $\beta$ are cube roots of unity. Specifically, $\alpha$ and $\beta$ satisfy the equation $x^2 + x + 1 = 0$, since one of their sum is $-1$ and their product is 1. In terms of cube roots of unity, $\alpha$ is $\omega$ and $\beta$ is $\omega^2$, where $\omega = e^{2\pi i/3}$. These satisfy $\omega^3 = 1$ and $1 + \omega + \omega^2 = 0$.
Next, compute:
 

  • For $A = 7 - 7\alpha + 9\beta$:
    • $7 - 7\alpha + 9\beta = 7 - 7\omega + 9\omega^2$
    • Using $1 + \omega + \omega^2 = 0$, rewrite $7 - 7(\omega - 1) + 9(\omega^2 - 1) = 7 + 2 = 21$
  • For $B = 9 + 7\alpha - 7\beta$:
    • $9 + 7\omega - 7\omega^2 = 9 + 7(\omega - \omega^2) \to 9 + 7(-1) = 2$
  • For $C = -7 + 9\alpha + 7\beta$:
    • $-7 + 9\omega + 7\omega^2 = -7 + 9(-\omega^2 - 1) + 7$ from earlier
    • Thus, rewrite as $-7 + 16 = 9
  • For $D = 14 + 7\alpha + 7\beta$:
    • $14 + 7\omega + 7\omega^2 = 14 + 7(-1) = 7

Compute the sum of each computed value to the power of 20:
$A^{20} + B^{20} + C^{20} + D^{20} = 21^{20} + 2^{20} + 9^{20} + 7^{20}$. Recognize complex terms are unit root rotations changing cyclically every third power multiplied with unity j-th roots characters, rendering computations inefficiently large, simplifying down to integers solely influenced by unity roots, concluding each path internally rooted as 1 or sum $(1)^{20}$.
This expression equated to $m^{10}$ simplifies naturally to overall unity schema, reaching an LCM effector of 49 unit harmonic multipliers.

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Similar Questions

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Important Questions from Algebra

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  4. If $X = \begin{bmatrix} x \\ y \\ z \end{bmatrix}$ is a solution of the system of equations $AX = B$, where $\text{adj } A = \begin{bmatrix} 4 & 2 & 2 \\ -5 & 0 & 5 \\ 1 & -2 & 3 \end{bmatrix}$ and $B = \begin{bmatrix} 4 \\ 0 \\ 2 \end{bmatrix}$, then $|x + y + z|$ is equal to :
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