CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2006

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

    A)  \[x-y+1=0\]      

    B)  \[x+y+1=0\]

    C)  \[2x-y+1=0\] 

    D)         \[x+2y+2=0\]

    E)  \[2x+y-1=0\]

    Correct Answer: A

    Solution :

    \[y={{(1+x)}^{y}}+{{\sin }^{-1}}({{\sin }^{2}}x)\] At           \[x=0,y=1\] Let \[y=u+v\]   where \[u={{(1+x)}^{y}},\] \[v={{\sin }^{-1}}({{\sin }^{2}}x)\] \[\Rightarrow \]               \[\log u=y\log (1+x)\]    \[\Rightarrow \]               \[\frac{dy}{dx}\frac{1}{u}=\frac{y}{1+x}+\log (1+x)\frac{dy}{dx}\] and \[\frac{dv}{dx}=\frac{1}{\sqrt{1-{{\sin }^{2}}x}}.2\sin x\cos x\] \[\therefore \] \[\frac{dy}{dx}={{(1+x)}^{y}}\left[ \frac{y}{1+x}+\log (1+x)\frac{dy}{dx} \right]\]                                                 \[+\frac{\sin 2x}{\cos x}\] \[\frac{dy}{dx}[1-{{(1+x)}^{y}}\log (x+1)]\]                 \[=\frac{{{(1+x)}^{y}}y}{1+x}+\frac{\sin 2x}{\cos x}\] \[\therefore \]  \[{{\left. \frac{dy}{dx} \right|}_{(0,1)}}=\frac{1}{1+0}=1\] \[\therefore \]Equation of tangent is \[(y-1)=1(x)\Rightarrow y-x-1=0\] \[\Rightarrow \]               \[x-y+1=0\]


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