CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    If\[\int_{a}^{0}{\frac{{{x}^{2}}-1}{1-x}dx=-\frac{1}{2},}\]then the value of a is equal to

    A)  \[-1\]   

    B)                         \[1\]

    C)  \[2\]                    

    D)         \[-2\]

    E)  \[-\frac{1}{2}\]

    Correct Answer: A

    Solution :

    \[\int_{a}^{0}{\frac{{{x}^{2}}-1}{1-x}dx=-\frac{1}{2}}\] \[\Rightarrow \]               \[\int_{0}^{a}{\frac{(x-1)(x+1)}{(x-1)}}dx=-\frac{1}{2}\] \[\Rightarrow \]               \[\int_{0}^{a}{(x+1)}dx=-\frac{1}{2}\] \[\Rightarrow \]               \[[{{x}^{2}}/2+x]_{0}^{a}=-\frac{1}{2}\] \[\Rightarrow \]               \[{{a}^{2}}/2+a=-\frac{1}{2}\] \[\Rightarrow \]               \[{{a}^{2}}+2a+1=0\]                 \[{{(a+1)}^{2}}=0\] \[\Rightarrow \]               \[a=-1\]


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