Railways R.R.C. (Hazipur) Solved Paper Held on 27-10-2013

  • question_answer
    If \[\frac{x}{y}=\frac{1}{3}\],then \[\frac{{{x}^{2}}+{{y}^{2}}}{{{x}^{2}}-{{y}^{2}}}=?\]

    A) \[-\frac{10}{9}\]            

    B) \[\frac{5}{4}\]

    C) \[-\frac{5}{4}\]                         

    D) \[-\frac{5}{3}\]

    Correct Answer: C

    Solution :

    \[\frac{{{x}^{2}}+{{y}^{2}}}{{{x}^{2}}-{{y}^{2}}}=\frac{\left( \frac{{{x}^{2}}}{{{y}^{2}}} \right)+1}{\left( \frac{{{x}^{2}}}{{{y}^{2}}} \right)-1}=\frac{{{\left( \frac{x}{y} \right)}^{2}}+1}{{{\left( \frac{x}{y} \right)}^{2}}-1}\] \[=\frac{{{\left( \frac{1}{3} \right)}^{2}}+1}{\left( \frac{1}{3} \right)-1}=\frac{\frac{10}{9}}{-\frac{8}{9}}=-\frac{5}{4}\]


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