JEE Main & Advanced Sample Paper JEE Main - Mock Test - 41

  • question_answer
    The equation of the normal to the curve \[y={{(1+x)}^{y}}+{{\sin }^{-1}}(si{{n}^{2}}x)\] at \[x=0\]is

    A) \[x+y=1\]           

    B)        \[x+y+1=0\]

    C) \[2x-y+1=0\]    

    D)        \[x+2y+2=0\]

    Correct Answer: A

    Solution :

    We have,  \[y={{(1+x)}^{y}}+{{\sin }^{-1}}\left( {{\sin }^{2}}x \right)\]  ...(i) when \[x=0,\]we have \[y=1\] Differentiating (i) w.r.t. x we get \[\frac{dy}{dx}={{\left( 1+x \right)}^{y}}\left\{ \frac{dy}{dx}\log (1+x)+\frac{y}{1+x} \right\}+\frac{\sin 2x}{\sqrt{1-{{\sin }^{4}}x}}\]\[\Rightarrow \,\,{{\left( \frac{dy}{dx} \right)}_{(0,1)}}=1\Rightarrow -{{\left( \frac{dx}{dy} \right)}_{(0,1)}}=-1.\] So the equation of the normal at \[(0,1)\] is             \[y-1=-1\left( x-0 \right)\Rightarrow x+y=1\]


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