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For a variable x satisfying x - 1/x = 4, evaluate x^2 + 1/x^2.

A14
B18
C16
D20
Answer & Solution
Correct answer: B. 18
Given x - 1/x = 4, squaring both sides yields x^2 + 1/x^2 - 2 = 16, so x^2 + 1/x^2 = 18.
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