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If $$x = 5 + 2\sqrt 6 {\text{,}}$$    then the value of $$\left( {\sqrt x + \frac{1}{{\sqrt x }}} \right)\,{\text{is?}}$$

A. $${\text{2}}\sqrt 2 $$

B. $${\text{3}}\sqrt 2 $$

C. $${\text{2}}\sqrt 3 $$

D. $${\text{3}}\sqrt 3 $$

Answer: Option C

Solution(By Examveda Team)

$$\eqalign{ & x = 5 + 2\sqrt 6 \cr & \Leftrightarrow x = 3 + 2 + 2\sqrt 3 \times \sqrt 2 \cr & \Leftrightarrow x = {\left( {\sqrt 3 } \right)^2} + {\left( {\sqrt 2 } \right)^2} + 2\sqrt 3 \times \sqrt 2 \cr & \Leftrightarrow x = {\left( {\sqrt 3 + \sqrt 2 } \right)^2} \cr & \Leftrightarrow \sqrt x = \sqrt 3 + \sqrt 2 \cr & {\text{Similarly,}} \cr & \Leftrightarrow \frac{1}{{\sqrt x }} = \sqrt 3 - \sqrt 2 \cr & \therefore \left( {\sqrt x + \frac{1}{{\sqrt x }}} \right) \cr & = \sqrt 3 + \sqrt 2 + \sqrt 3 - \sqrt 2 \cr & = 2\sqrt 3 \cr} $$

This Question Belongs to Arithmetic Ability >> Algebra

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