VIT Engineering VIT Engineering Solved Paper-2014

  • question_answer
    The solution of \[\frac{dy}{dx}=\frac{{{x}^{2}}+{{y}^{2}}+1}{2xy},\] satisfying y(1) = 0 is given by

    A) hyperbola          

    B) circle

    C) ellipse                  

    D) parabola

    Correct Answer: A

    Solution :

    Given differentia equation is                \[={{\left( 3.04\times {{10}^{-8}}cm \right)}^{3}}\] \[=2.81\times {{10}^{-23}}c{{m}^{3}}\]      \[2xydy=({{x}^{2}}+1)dx+{{y}^{2}}dx\] \[=2.81\times {{10}^{-23}}c{{m}^{3}}\]   \[\frac{xd\left( {{y}^{2}} \right)-{{y}^{2}}dx}{{{x}^{2}}}=\left( \frac{{{x}^{2}}+1}{{{x}^{2}}} \right),,dx\] \[=2.81\times {{10}^{-23}}c{{m}^{3}}\]     \[\int{d\left( \frac{{{y}^{2}}}{x} \right)=\int{\left( 1+\frac{1}{{{x}^{2}}} \right)dx}}\] \[=2.81\times {{10}^{-23}}c{{m}^{3}}\]          \[\frac{{{y}^{2}}}{x}=x-\frac{1}{x}+C\] \[=2.81\times {{10}^{-23}}c{{m}^{3}}\]               \[{{y}^{2}}=\left( {{x}^{2}}-1+Cx \right)\] When               x = 1, y = 0 Then,               0 = 1 ? 1 + C \[=2.81\times {{10}^{-23}}c{{m}^{3}}\]                     C = 0 \[\therefore \]   The solution is  \[{{x}^{2}}-{{y}^{2}}=1i.e.,\] hyperbola.


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