CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2008

  • question_answer
    The integrating factor of the differential equation \[\frac{dy}{dx}+\frac{y}{(1-x)\sqrt{x}}=1-\sqrt{x}\]is

    A)  \[\frac{1-\sqrt{x}}{1+\sqrt{x}}\]                              

    B)  \[\frac{1+\sqrt{x}}{1-\sqrt{x}}\]

    C)  \[\frac{1-x}{1+x}\]         

    D)         \[\frac{\sqrt{x}}{1-\sqrt{x}}\]

    E)  \[\frac{\sqrt{x}}{1+\sqrt{x}}\]

    Correct Answer: B

    Solution :

    Given differential equation is \[\frac{dy}{dx}+\frac{y}{(1-x)\sqrt{x}}=1-\sqrt{x}\] Here, \[P=\frac{1}{(1-x)\sqrt{x}}\] \[\therefore \]  \[IF={{e}^{\int{P}\,dx}}={{e}^{\int{\frac{1}{(1-x)\sqrt{x}}}dx}}\] Put\[\sqrt{x}=t\Rightarrow \frac{1}{2\sqrt{x}}dx=dt\] \[\therefore \]  \[IF={{e}^{\int{\frac{2}{1-{{t}^{2}}}dt}}}\]                 \[={{e}^{\frac{2}{2}\log \left( \frac{1+t}{1-t} \right)}}=\frac{1+t}{1-t}\]                 \[=\frac{1+\sqrt{x}}{1-\sqrt{x}}\]


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