JEE Main & Advanced Mathematics Functions Question Bank Self Evaluation Test - Relations and Functions-I

  • question_answer
    If f(x) = x and \[g(x)=\left| x \right|\], then \[(f+g)(x)\] is equal to

    A) 0 for all \[x\in R\]

    B)        2x for all \[x\in R\]

    C) \[\left\{ \begin{matrix}    2x,for\,\,x\ge 0  \\    0,for\,\,x<0  \\ \end{matrix} \right.\]

    D)        \[\left\{ \begin{matrix}    0,for\,\,x\ge 0  \\    2x,for\,\,x<0  \\ \end{matrix} \right.\]

    Correct Answer: C

    Solution :

    [c] Given functions are: \[f(x)=x\] and \[g(x)=\left| x \right|\] \[\therefore (f+g)(x)=f(x)+g(x)=x+\left| x \right|\] According to definition of modulus function, \[(f+g)(x)=\left\{ \begin{matrix}    x+x,\,\,x\ge 0  \\    x-x,\,\,x<0  \\ \end{matrix}=\left\{ \begin{matrix}    2x,\,\,x\ge 0  \\    0,\,\,x<0  \\ \end{matrix} \right. \right.\]


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