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Examveda

If $$x = 5 + 2\sqrt 6 {\text{,}}$$    then $$\sqrt x - \frac{1}{{\sqrt x }}$$   = is?

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

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

C. $$\sqrt 3 + \sqrt 2 $$

D. $$\sqrt 3 - \sqrt 2 $$

Answer: Option A

Solution(By Examveda Team)

$$\eqalign{ & {\left( {\sqrt x - \frac{1}{{\sqrt x }}} \right)^2} \cr & = x + \frac{1}{x} - 2 \cr & = \left( {5 + 2\sqrt 6 } \right) + \frac{1}{{\left( {5 + 2\sqrt 6 } \right)}} - 2 \cr & = \left( {5 + 2\sqrt 6 } \right) + \frac{1}{{\left( {5 + 2\sqrt 6 } \right)}} \times \frac{{\left( {5 - 2\sqrt 6 } \right)}}{{\left( {5 - 2\sqrt 6 } \right)}} - 2 \cr & = \left( {5 + 2\sqrt 6 } \right) + \left( {5 - 2\sqrt 6 } \right) - 2 \cr & = 10 - 2 \cr & = 8 \cr & \therefore \left( {\sqrt x - \frac{1}{{\sqrt x }}} \right) = \sqrt 8 = 2\sqrt 2 \cr} $$

This Question Belongs to Arithmetic Ability >> Surds And Indices

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