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Examveda

If x4 + x-4 = 194, x > 0, then what is the value of $$x + \frac{1}{x} + 2?$$

A. 6

B. 8

C. 4

D. 14

Answer: Option A

Solution(By Examveda Team)

$$\eqalign{ & {x^4} + {x^{ - 4}} = 194 \cr & {\left( {{x^2} + \frac{1}{{{x^2}}}} \right)^2} = 194 + 2 \cr & {\left( {{x^2} + \frac{1}{{{x^2}}}} \right)^2} = 196 \cr & {x^2} + \frac{1}{{{x^2}}} = 14 \cr & x + \frac{1}{x} = {\left( {16} \right)^{\frac{1}{2}}} \cr & x + \frac{1}{x} = 4 \cr & x + \frac{1}{x} + 2 = 4 + 2 \cr & x + \frac{1}{x} = 6 \cr} $$

This Question Belongs to Arithmetic Ability >> Algebra

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