JEE Main & Advanced Mathematics Applications of Derivatives Question Bank Mock Test - Application of Derivatives

  • question_answer
    The normal to the curve \[2{{x}^{2}}+{{y}^{2}}=12\] at the point (2, 2) cuts the curve again at

    A) \[\left( -\frac{22}{9},-\frac{2}{9} \right)\] 

    B) \[\left( \frac{22}{9},\frac{2}{9} \right)\]

    C) \[\left( -\,2,\,\,-2 \right)\]  

    D) none of these

    Correct Answer: A

    Solution :

    [a] \[2{{x}^{2}}+{{y}^{2}}=12\] or \[\frac{dy}{dx}=-\frac{2x}{y}\]. Slope of normal at point A (2, 2) is\[\frac{1}{2}\]. Also, point \[B\left( -\frac{22}{9},-\frac{2}{9} \right)\]lies on the curve and slope of AB is \[\frac{2-(-2/9)}{2-(-22/9)}=\frac{1}{2}\] Hence, the normal meets the curve again at point \[\left( -\frac{22}{9},-\frac{2}{9} \right)\].


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