If x^{2}-x+1=0 then what is (x-\frac{1}{x})^{2}+(x-\frac{1}{x})^{4}+(x-\frac{1}{x})^{8} equal to?

  1. A. 81
  2. B. 85
  3. C. 87
  4. D. 90

Correct Answer: C. 87

Explanation

x^2-x+1=0 \implies x+1/x=1. Then (x-1/x)^2 = (x+1/x)^2 - 4 = 1 - 4 = -3. The required expression is (-3) + (-3)^2 + (-3)^4 = -3 + 9 + 81 = 87.

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