If (x + 1/x) = 2, then (x3 + 1/x3) is equal to :
Option:
A. 64
B. 14
C. 8
D. 2
Answer: D . 2
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Justification:
x + 1/x = 2
→ ( x + 1/x)3 = 23
→ x3 + 1/x3 +3(x + 1/x) = 8
→ x3 + 1/x3 + 3 x 2 = 8
→ x3 + 1/x3 = 2.
