InterviewSolution
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If \(\sqrt {\rm{x}} + \frac{1}{{\sqrt {\rm{x}} }} = {\rm{\;}}3\) then what will be the value of \(\frac{{\left( {x + \frac{1}{x}} \right)\; + \left( {{x^2} + \frac{1}{{{x^2}}}} \right)}}{2}\)1. 252. 273. 264. 23 |
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Answer» Correct Answer - Option 2 : 27 Given: \(\sqrt {\rm{x}} + \frac{1}{{\sqrt {\rm{x}} }} = {\rm{\;}}3\) Formula used: \({{\rm{a}}^2} + \frac{1}{{{{\rm{a}}^2}}} = {{\rm{c}}^2} - {\rm{\;}}2\) Calculation: \(\sqrt {\rm{x}} + \frac{1}{{\sqrt {\rm{x}} }} = {\rm{\;}}3\) ⇒ \({\rm{x}} + \frac{1}{{{\rm{x}}}} = {\rm{\;}}3^2 - 2\) ⇒ \({\rm{x}} + \frac{1}{{{\rm{x}}}} = {\rm{\;}}9 - 2\) ⇒ \({\rm{x}} + \frac{1}{{{\rm{x}}}} = {\rm{\;}}7\) ⇒ \({\rm{x^2}} + \frac{1}{{{\rm{x^2}}}} = {\rm{\;}}7^2 - 2\) ⇒ \({\rm{x^2}} + \frac{1}{{{\rm{x^2}}}} = {\rm{\;}}49 - 2\) ⇒ \({\rm{x^2}} + \frac{1}{{{\rm{x^2}}}} = {\rm{\;}}47\) \(\frac{{\left( {x + \frac{1}{x}} \right)\; + \left( {{x^2} + \frac{1}{{{x^2}}}} \right)}}{2}\) ⇒ (7 + 47)/2 ⇒ 54/2 ⇒ 27 ∴ Required value is 27 |
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