Manipal Engineering Manipal Engineering Solved Paper-2011

  • question_answer
    The function\[f(x)=\max \{(1-x),\,\,(1+x),\,\,2\}\],\[x\in (-\infty ,\,\,\infty )\]is equivalent to

    A) \[f(x)=\left\{ \begin{matrix}    1+x & , & x\le -1  \\    2 & , & -1<x<1  \\    1-x & , & x\ge 1  \\ \end{matrix} \right.\]

    B) \[f(x)=\left\{ \begin{matrix}    1-x & , & x\le -1  \\    2 & , & -1<x<1  \\    1+x & , & x\ge 1  \\ \end{matrix} \right.\]

    C) \[f(x)=\left\{ \begin{matrix}    1-x & , & x\le -1  \\    1 & , & -1<x<1  \\    1+x & , & x\ge 1  \\ \end{matrix} \right.\]

    D) None of the above

    Correct Answer: B

    Solution :

    Given that, \[f(x)=\max \{(1-x),\,\,2,\,\,(1+x)\}\] For\[x\le -1\], we find that\[1-x\ge 2\] and\[1-x\ge 1+x\] \[\therefore \]\[\max \{(1-x),\,\,2(1+x)\}=1-x\] For\[-1<x<1\], we find that \[0<1-x<2\]and\[0<1+x<2\] \[\therefore \]\[\max \{(1-x),\,\,2,\,\,(1+x)\}=1+x\] For\[x\ge 1\], we find that                 \[1+x\ge 2,\,\,1+x>1-x\] \[\therefore \]\[\max \{(1-x),\,\,2,\,\,(1+x)\}=1+x\] Hence,\[f(x)=\left\{ \begin{matrix}    1-x, & x\le -1  \\    2, & -1<x<1  \\    1+x, & x\ge 1  \\ \end{matrix} \right.\]


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