EduGoog

If (x + 1/x) = 4, then (x41/x4) is equal to :

Option:
A. 196
B. 194
C. 192
D. 190
Answer: B . 194

Justification:

x + 1/x = 4 → ( x + 1/x)2 = 16 → x2 + 1/x2 + 2 = 16 → x2 +1/x2 = 14

Now,

x2 + 1/x2 = 14 → ( x2 + 1/x2)2 = 196 → x4 + 1/x4 + 2 = 196 → x4 +1/x4 = 194.

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