JEE Main & Advanced Mathematics Relations Question Bank Mock Test - Relations and Functions

  • question_answer
    If \[f(x)\] is an invertible function and \[g\left( x \right)=2f\left( x \right)+5,\] then the value of \[{{g}^{-1}}(x)\] is

    A) \[2{{f}^{-1}}(x)-5\]     

    B) \[\frac{1}{2{{f}^{-1}}(x)+5}\]

    C) \[\frac{1}{2}{{f}^{-1}}(x)=5\] 

    D) \[{{f}^{-1}}\left( \frac{x-5}{2} \right)\]

    Correct Answer: D

    Solution :

    [d] Replacing \[x\] by \[{{g}^{-1}}(x)\], we get \[x=2f({{g}^{-1}}(x))+5\] \[\therefore f({{g}^{-1}}(x))=\frac{x-5}{2}\] \[\therefore {{g}^{-1}}(x)={{f}^{-1}}\left( \frac{x-5}{2} \right)\]


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