JEE Main & Advanced Sample Paper JEE Main Sample Paper-3

  • question_answer
    If \[y={{e}^{x}}+\sin x,\]then \[{{d}^{2}}x/d{{y}^{2}}\]is equal to

    A)  \[{{e}^{x}}-\sin x\]

    B)  \[-{{({{e}^{x}}+\cos x)}^{-2}}\]

    C)  \[-({{e}^{x}}-\sin x)\,\,{{({{e}^{x}}+\cos x)}^{-2}}\]

    D)  \[(\sin x-{{e}^{x}})\,\,{{(\cos x+{{e}^{x}})}^{-3}}\]

    Correct Answer: D

    Solution :

     \[y={{e}^{x}}+\sin x\] \[\frac{dy}{dx}={{e}^{x}}+\cos x\Rightarrow \frac{dx}{dy}=\frac{1}{{{e}^{x}}+\cos x}\] Diff. w.r.t y \[\frac{{{d}^{2}}x}{d{{y}^{2}}}=\frac{-1[{{e}^{x}}-\sin x]}{{{({{e}^{x}}+\cos x)}^{2}}}\times \frac{dx}{dy}=\frac{(\sin x-{{e}^{x}})}{{{({{e}^{x}}+\cos x)}^{3}}}\]


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