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

  • question_answer
    If \[y={{\sqrt{x}}^{{{\sqrt{x}}^{\sqrt{x}....\infty }}}}\], then \[\frac{dy}{dx}=\]

    A)            \[\frac{{{y}^{2}}}{2x-2y\log x}\]

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

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

    D)            None of these

    Correct Answer: D

    Solution :

               \[y={{\sqrt{x}}^{{{\sqrt{x}}^{\sqrt{x}.....\infty }}}}\Rightarrow y={{(\sqrt{x})}^{y}}\]                    Þ  \[\log y=y\log {{x}^{1/2}}=\frac{1}{2}y\log x\]                    Þ  \[\frac{1}{y}\frac{dy}{dx}=\frac{1}{2}\left( \log x\frac{dy}{dx}+\frac{y}{x} \right)\Rightarrow \frac{dy}{dx}\left( \frac{2}{y}-\log x \right)=\frac{y}{x}\]                    Þ  \[\frac{dy}{dx}=\frac{y.y}{x(2-y\log x)}=\frac{{{y}^{2}}}{x(2-y\log x)}\].


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