CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2003

  • question_answer
    The point on the curve\[\sqrt{x}+\sqrt{y}=\sqrt{a},\]the normal at which is parallel to the\[x-\]axis, is:

    A)  \[(0,0)\]                             

    B)  \[(0,a)\]

    C)  \[(a,0)\]             

    D)        \[(a,a)\]

    E)  \[(-a,a)\]

    Correct Answer: B

    Solution :

    The equation of given curve is\[\sqrt{x}+\sqrt{y}=\sqrt{a}\] \[\therefore \]  \[\frac{1}{2\sqrt{x}}+\frac{1}{2\sqrt{y}}\frac{dy}{dx}=0\] \[\Rightarrow \]               \[\frac{dy}{dx}=-\frac{\sqrt{y}}{\sqrt{x}}\] The normal is parallel to\[x-\]axis, if \[{{\left( \frac{dx}{dy} \right)}_{({{x}_{1}},{{y}_{1}})}}=0\] \[\Rightarrow \]               \[\sqrt{{{x}_{1}}}=0\] \[\Rightarrow \]               \[{{x}_{1}}=0\] \[\therefore \]From equation of curve\[{{y}_{1}}=a\]. \[\therefore \]Required point is\[(0,a)\].


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