JCECE Engineering JCECE Engineering Solved Paper-2012

  • question_answer
    If\[f(x)={{[1-{{(x-3)}^{4}}]}^{1/7}}\], find\[{{f}^{-1}}(x)\].

    A) \[3+{{(1-x)}^{7/4}}\]                      

    B) \[3+{{(1-{{x}^{4}})}^{7}}\]

    C) \[3+{{(1-{{x}^{7}})}^{1/4}}\]                       

    D) \[3-{{(1-{{x}^{4}})}^{1/7}}\]

    Correct Answer: C

    Solution :

    Let\[y=f(x)={{[1-{{(x-3)}^{4}}]}^{1/7}}\] \[\Rightarrow \]               \[{{y}^{7}}=1-{{(x-3)}^{4}}\] \[\Rightarrow \]               \[{{(x-3)}^{4}}=1-{{y}^{7}}\] \[\Rightarrow \]               \[x=3+{{(1-{{y}^{7}})}^{1/4}}\] \[\Rightarrow \]               \[{{f}^{-1}}(y)=3+{{(1-{{y}^{7}})}^{1/4}}\] \[\Rightarrow \]               \[{{f}^{-1}}(x)=3+{{(1-{{x}^{7}})}^{1/4}}\]


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