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Examveda

If $$x = 3 + 2\sqrt 2 {\text{,}}$$    then the value of $$\left( {\sqrt x - \frac{1}{{\sqrt x }}} \right){\text{ is?}}$$

A. 1

B. 2

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

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

Answer: Option B

Solution(By Examveda Team)

$$\eqalign{ & x = 3 + 2\sqrt 2 \cr & \Rightarrow x = 2 + 1 + 2\sqrt 2 \cr & \Rightarrow x = {\left( {\sqrt 2 + 1} \right)^2} \cr & \Rightarrow \sqrt x = \sqrt 2 + 1 \cr & \Rightarrow \frac{1}{{\sqrt x }} = \frac{1}{{\sqrt 2 + 1}} \cr & \Rightarrow \frac{1}{{\sqrt x }} = \frac{1}{{\sqrt 2 + 1}} \times \frac{{\sqrt 2 - 1}}{{\sqrt 2 - 1}} \cr & \Rightarrow \frac{1}{{\sqrt x }} = \sqrt 2 - 1 \cr & \therefore \sqrt x - \frac{1}{{\sqrt x }} \cr & = \sqrt 2 + 1 - \left( {\sqrt 2 - 1} \right) \cr & = \sqrt 2 + 1 - \sqrt 2 + 1 \cr & = 2 \cr} $$

This Question Belongs to Arithmetic Ability >> Algebra

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