2. Solved Papers
  3. JEE Main & Advanced

JEE Main & Advanced JEE Main Paper (Held on 10-4-2019 Afternoon)

  • question_answer
    Let \[f(x)\,\,\,=\,\,\,lo{{g}_{e}}(sin\,x),\,\,\,\,\,\,(0<x<\pi )\] and \[g(x)={{\sin }^{-1}}({{e}^{-\,x}}),(x\ge 0).\]If \[\alpha \]is a positive real number such that \[a=(fog)'(\alpha )\] and \[b=(fog)(\alpha ),\]then : [JEE Main 10-4-2019 Afternoon]

    A) \[a{{\alpha }^{2}}-b\alpha -a=0\]

    B) \[a{{\alpha }^{2}}+b\alpha -a=-2{{\alpha }^{2}}\]

    C) \[a{{\alpha }^{2}}+b\alpha +a=0\]

    D) \[a{{\alpha }^{2}}-b\alpha -a=1\]

    Correct Answer: D

    Solution :

    \[fog(x)=(-x)\Rightarrow (fg(\alpha ))=-\alpha =b\]           \[(fg(x))'=-1\Rightarrow (fg(\alpha ))'=-1=a\]


You need to login to perform this action.
You will be redirected in 3 sec spinner