JEE Main & Advanced JEE Main Solved Paper-2017

  • question_answer
    A hyperbola passes through the point \[\text{P(}\sqrt{\text{2}}\text{,}\sqrt{\text{3}}\text{)}\]and has foci at \[(\pm \,2,0).\]Then the tangent to this hyperbola at P is also passes through the point:                  JEE Main Solved Paper-2017

    A)  \[\left( -\sqrt{2},-\sqrt{3} \right)\]         

    B)  \[\left( 3\sqrt{2},2\sqrt{3} \right)\]

    C)  \[\left( 2\sqrt{2},3\sqrt{3} \right)\]                        

    D)  \[\left( \sqrt{3},\sqrt{2} \right)\]

    Correct Answer: C

    Solution :

     Equation of hyperbola is \[\frac{{{x}^{2}}}{{{a}^{2}}}-\frac{{{y}^{2}}}{{{b}^{2}}}=1\]                 foci is \[(\pm \,2,0)\]hence \[ae=2,\Rightarrow {{a}^{2}}{{e}^{2}}=4\]                 \[{{b}^{2}}={{a}^{2}}({{e}^{2}}-1)\] \[\therefore \]  \[{{a}^{2}}+{{b}^{2}}=4\]                              ?. Hyperbola passes through \[\left( \sqrt{2},\sqrt{3} \right)\] \[\therefore \]  \[\frac{2}{{{a}^{2}}}-\frac{3}{{{b}^{2}}}=1\]                          ?. On solving [a] and [b] \[{{a}^{2}}=8\](is rejected) and \[{{a}^{2}}=1\]and \[{{b}^{2}}=3\] \[\therefore \]  \[\frac{{{x}^{2}}}{1}-\frac{{{y}^{3}}}{3}=1\] Equation of tangent is \[\frac{\sqrt{2x}}{1}-\frac{\sqrt{3y}}{3}=1\] Hence \[\left( 2\sqrt{2},3\sqrt{3} \right)\]satisfy it.


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