JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2012

  • question_answer
        The slope of the tangent at\[(x,y)\]to a curve passing through a point (2, 1) is\[\frac{{{x}^{2}}+{{y}^{2}}}{2xy}\],then the equation of the curve is

    A)  \[2({{x}^{2}}-{{y}^{2}})=3x\]     

    B)  \[2({{x}^{2}}-{{y}^{2}})=6y\]

    C)  \[x({{x}^{2}}-{{y}^{2}})=6\]        

    D)  \[x({{x}^{2}}+{{y}^{2}})=10\]

    Correct Answer: A

    Solution :

                    Let \[I=\int{\frac{{{e}^{x}}\,dx}{\sqrt{5-4{{e}^{x}}-{{e}^{2x}}}}}\] Put\[{{e}^{x}}=t\] \[\Rightarrow \]                               \[{{e}^{x}}dx=dt\] \[\therefore \]                  \[I=\int{\frac{dt}{\sqrt{5-4t-{{t}^{2}}}}}\]                                 \[=\int{\frac{dt}{\sqrt{5({{t}^{2}}+4t+4)+4}}}\]                                 \[I=\int{\frac{dt}{\sqrt{9-{{(t+2)}^{2}}}}}\] \[\Rightarrow \]               \[I={{\sin }^{-1}}\left( \frac{t+2}{3} \right)+c\] \[\Rightarrow \]               \[I={{\sin }^{-1}}\left( \frac{{{e}^{x}}+2}{3} \right)+c\]


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