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Given that $x - 1/ x = 2$ , what does $x^{4} + 1/ x^{4}$ equal?

Competition practiceAlgebra

A34
B36
C38
D16

Step-by-Step Solution

Squaring,

x^{2} - 2 + 1/ x^{2} = 4

, so

x^{2} + 1/ x^{2} = 6

. Squaring again,

x^{4} + 2 + 1/ x^{4} = 36

, so

x^{4} + 1/ x^{4} = 34

.

Answer: A) 34

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