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

  • question_answer
    Let \[f(x)\] be define on \[[-2,2]\] and is given by \[f(x)=\left\{ \begin{matrix}    -1,\,-2\le x\le 0  \\    x-1,\,0\le x\le 2  \\ \end{matrix} \right.\], then \[f(\left| x \right|)\] is defined as

    A) \[f(\left| x \right|)=\left\{ \begin{matrix}    1-2\le x\le 0  \\    1-x,0<x\le 2  \\ \end{matrix} \right.\]

    B) \[f(\left| x \right|)=x-1\forall x\in R\]

    C) \[f(\left| x \right|)=\left\{ \begin{matrix}    -x-1,-2\le x\le 0  \\    x-1,0<x\le 2  \\ \end{matrix} \right.\]

    D) None of these

    Correct Answer: C

    Solution :

    [c] we have \[f(x)=\left\{ \begin{matrix}    -1,-2\le x\le 0  \\    x-1,0\le x\le 2  \\ \end{matrix} \right.\] \[f(\left| x \right|)=\left\{ \begin{matrix}    -1,-2\le \left| x \right|\le 0  \\    \left| x \right|-1,0\le \left| x \right|\le 2  \\ \end{matrix} \right.\Rightarrow f(\left| x \right|)=\left| x \right|-1,0\le \left| x \right|\le 2\](\[(as-2\le \left| x \right|\le 0\] is not possible) \[\Rightarrow f(\left| x \right|)=\left\{ \begin{matrix}    -x-1,  \\    x-1,  \\ \end{matrix}\,\,\,\begin{matrix}    -2\le x\le 0  \\    0<x\le 2  \\ \end{matrix}\begin{matrix}    {}  \\    {}  \\ \end{matrix} \right.\]


You need to login to perform this action.
You will be redirected in 3 sec spinner