JCECE Engineering JCECE Engineering Solved Paper-2012

  • question_answer
    The minimum value of\[f(x)=|x-1|+|x-2|+|x-3|\] is equal to

    A) \[1\]                                     

    B) \[2\]

    C) \[3\]                                     

    D) \[0\]

    Correct Answer: B

    Solution :

    Given function can be rewritten as                 \[f(x)=\left\{ \begin{matrix}    6-3x, & x<1  \\    4-x, & 1\le x<2  \\    x, & 2\le x<3  \\    3x-6, & x\ge 3  \\ \end{matrix} \right.\] \[\Rightarrow \]               \[f'(x)=\left\{ \begin{matrix}    -3, & x<1  \\    -1, & 1<x<2  \\    1, & 2<x<3  \\    3, & x>3  \\ \end{matrix} \right.\] Thus, \[f(x)\] is increasing for \[x<2\] and increasing for\[x>2\]. Hence, \[f(x)\] is minimum for\[x=2\] and        \[{{[f(x)]}_{\min }}=f(2)=2\]


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