CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    \[\underset{x\to 1}{\mathop{\lim }}\,\frac{{{x}^{2}}-2x+1}{|{{x}^{2}}-1|}\]is equal to:

    A)  0                                            

    B)  1

    C)  \[-1\]                   

    D)         2

    E)  does not exist

    Correct Answer: A

    Solution :

    \[\underset{x\to 1}{\mathop{\lim }}\,\frac{{{x}^{2}}-2x+1}{|{{x}^{2}}-1|}\] \[|{{x}^{2}}-1|=\left\{ \begin{matrix}    -({{x}^{2}}-1), & if-1<x<1  \\    {{x}^{2}}-1, & if\,x>1  \\ \end{matrix} \right.\] \[\therefore \]  \[\underset{x\to {{1}^{+}}}{\mathop{\lim }}\,\frac{{{x}^{2}}-2x+1}{{{x}^{2}}-1}=\underset{x\to 1}{\mathop{\lim }}\,\frac{2x-2}{2x}=0\] \[\underset{x\to {{1}^{-}}}{\mathop{\lim }}\,\frac{{{x}^{2}}-2x+1}{1-{{x}^{2}}}=\underset{x\to 1}{\mathop{\lim }}\,\frac{2x-2}{-2x}=0\] \[\therefore \]  \[\underset{x\to 1}{\mathop{\lim }}\,\frac{{{x}^{2}}-2x+1}{|{{x}^{2}}-1|}=0\]


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