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If $$x = 5 + 2\sqrt 6 {\text{,}}$$ then the value of $$\left( {\sqrt x + \frac{1}{{\sqrt x }}} \right)\,{\text{is?}}$$
Answer & Solution
Correct Answer:
Option
C
$$\eqalign{
& x = 5 + 2\sqrt 6 \cr
& \Leftrightarrow x = 3 + 2 + 2\sqrt 3 \times \sqrt 2 \cr
& \Leftrightarrow x = {\left( {\sqrt 3 } \right)^2} + {\left( {\sqrt 2 } \right)^2} + 2\sqrt 3 \times \sqrt 2 \cr
& \Leftrightarrow x = {\left( {\sqrt 3 + \sqrt 2 } \right)^2} \cr
& \Leftrightarrow \sqrt x = \sqrt 3 + \sqrt 2 \cr
& {\text{Similarly,}} \cr
& \Leftrightarrow \frac{1}{{\sqrt x }} = \sqrt 3 - \sqrt 2 \cr
& \therefore \left( {\sqrt x + \frac{1}{{\sqrt x }}} \right) \cr
& = \sqrt 3 + \sqrt 2 + \sqrt 3 - \sqrt 2 \cr
& = 2\sqrt 3 \cr} $$
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