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If $$x = 3 + 2\sqrt 2 {\text{,}}$$ then the value of $$\left( {\sqrt x - \frac{1}{{\sqrt x }}} \right){\text{ is?}}$$
Answer & Solution
Correct Answer:
Option
B
$$\eqalign{
& x = 3 + 2\sqrt 2 \cr
& \Rightarrow x = 2 + 1 + 2\sqrt 2 \cr
& \Rightarrow x = {\left( {\sqrt 2 + 1} \right)^2} \cr
& \Rightarrow \sqrt x = \sqrt 2 + 1 \cr
& \Rightarrow \frac{1}{{\sqrt x }} = \frac{1}{{\sqrt 2 + 1}} \cr
& \Rightarrow \frac{1}{{\sqrt x }} = \frac{1}{{\sqrt 2 + 1}} \times \frac{{\sqrt 2 - 1}}{{\sqrt 2 - 1}} \cr
& \Rightarrow \frac{1}{{\sqrt x }} = \sqrt 2 - 1 \cr
& \therefore \sqrt x - \frac{1}{{\sqrt x }} \cr
& = \sqrt 2 + 1 - \left( {\sqrt 2 - 1} \right) \cr
& = \sqrt 2 + 1 - \sqrt 2 + 1 \cr
& = 2 \cr} $$
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