JEE Main & Advanced Mathematics Functions Question Bank Functions

  • question_answer
    Let the function f be defined by \[f(x)=\frac{2x+1}{1-3x}\], then \[{{f}^{-1}}(x)\] is [Kerala (Engg.) 2002]

    A)                    \[\frac{x-1}{3x+2}\]

    B)            \[\frac{3x+2}{x-1}\]

    C)                    \[\frac{x+1}{3x-2}\]

    D)            \[\frac{2x+1}{1-3x}\]

    Correct Answer: A

    Solution :

               Let \[y=f(x)\] Þ \[y=\frac{2x+1}{1-3x}\] Þ \[y-3xy=2x+1\]                    Þ \[x=\frac{y-1}{3y+2}\] Þ \[{{f}^{-1}}(y)=\frac{y-1}{3y+2}\Rightarrow {{f}^{-1}}(x)=\frac{x-1}{3x+2}\].


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