JEE Main & Advanced Mathematics Differentiation Question Bank Differentiation of implicit function Parametric

  • question_answer
    If \[{{x}^{3}}+8xy+{{y}^{3}}=64\],then \[\frac{dy}{dx}=\] [AI CBSE 1979]

    A)            \[-\frac{3{{x}^{2}}+8y}{8x+3{{y}^{2}}}\]

    B)            \[\frac{3{{x}^{2}}+8y}{8x+3{{y}^{2}}}\]

    C)            \[\frac{3x+8{{y}^{2}}}{8{{x}^{2}}+3y}\]

    D)            None of these

    Correct Answer: A

    Solution :

               \[{{x}^{3}}+8xy+{{y}^{3}}=64\]\[\Rightarrow 3{{x}^{2}}+8\left( y+x\frac{dy}{dx} \right)+3{{y}^{2}}\frac{dy}{dx}=0\]                    \[\therefore \frac{dy}{dx}=-\frac{3{{x}^{2}}+8y}{8x+3{{y}^{2}}}\].


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