CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2001

  • question_answer
    The value of\[\int{\frac{{{e}^{x}}(2-{{x}^{2}})dx}{(1-x)\sqrt{1-{{x}^{2}}}}}\]is equal to:

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

    B)         \[{{e}^{x}}\sqrt{1+x}+c\]

    C)  \[{{e}^{x}}\sqrt{1-x}+c\]             

    D)         \[{{e}^{x}}\sqrt{\frac{1-x}{1+x}}+c\]

    E)  \[\sqrt{\frac{1+x}{1-x}}+c\]

    Correct Answer: A

    Solution :

    Let          \[I=\int{\frac{{{e}^{x}}(2-{{x}^{2}})dx}{(1-x)\sqrt{1-{{x}^{2}}}}}\] \[=\int{\frac{{{e}^{x}}(1-{{x}^{2}})}{(1-x)\sqrt{1-{{x}^{2}}}}dx}+\int{\frac{{{e}^{x}}}{(1-x)\sqrt{1-{{x}^{2}}}}}dx\] \[=\int{{{e}^{x}}}\sqrt{\frac{1+x}{1-x}}dx+\int{\frac{{{e}^{x}}}{(1-x)\sqrt{1-{{x}^{2}}}}}dx\] \[=\left[ {{e}^{x}}\sqrt{\frac{1+x}{1-x}}-\frac{1}{2}\int{\frac{d}{dx}}\sqrt{\frac{1+x}{1-x}}{{e}^{x}}dx \right]\]                                 \[+\int{\frac{{{e}^{x}}}{(1-x)\sqrt{1-{{x}^{2}}}}dx}\] \[={{e}^{x}}\sqrt{\frac{1+x}{1-x}}-\int{\frac{{{e}^{x}}}{(1-x)\sqrt{1-{{x}^{2}}}}}dx\]                                                 \[+\int{\frac{{{e}^{x}}}{(1-x)\sqrt{1-{{x}^{2}}}}}dx\] \[={{e}^{x}}\sqrt{\frac{1+x}{1-x}}+c\]


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