CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    The general solution of\[(x+1)\frac{dy}{dx}+1=2{{e}^{-y}}\]is.

    A)  \[{{e}^{y}}=2x+c\]

    B)  \[{{e}^{-y}}=2x+c\]

    C)  \[{{e}^{y}}(x+1)=2x+c\]

    D)  \[{{e}^{y}}(x+1)+c\]

    E)  \[{{e}^{y}}(x+1)=x+c\]

    Correct Answer: C

    Solution :

    \[(1+x)\frac{dy}{dx}+1=2{{e}^{-y}}\] \[\Rightarrow \]               \[{{e}^{y}}(1+x)\frac{dy}{dx}+{{e}^{y}}=2\] \[\Rightarrow \]               \[{{e}^{y}}(1+x)dy=(2-{{e}^{y}})dx\] \[\Rightarrow \]               \[{{e}^{y}}(1+x)dy+{{e}^{y}}dx=2\,dx\] \[\Rightarrow \]               \[d({{e}^{y}}(1+x))=2\,dx\] On integrating both sides, we get                 \[{{e}^{y}}(1+x)=2x+c\]


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