CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2009

  • question_answer
    If\[f(x)\]satisfies the relation\[2f(x)+f(1-x)={{x}^{2}}\]for all real\[x,\]then\[f(x)\]is

    A) \[\frac{{{x}^{2}}+2x-1}{6}\]                        

    B)  \[\frac{{{x}^{2}}+2x-1}{3}\]

    C)  \[\frac{{{x}^{2}}+4x-1}{3}\]       

    D)         \[\frac{{{x}^{2}}-3x+1}{6}\]

    E)  \[\frac{{{x}^{2}}+3x-1}{3}\]

    Correct Answer: B

    Solution :

    Given, \[2f(x)+f(1-x)={{x}^{2}}\]                                                  ...(i) Replacing\[x\]by\[(1-x),\]we get \[2f(1-x)+f(x)={{(1-x)}^{2}}\] \[\Rightarrow \]               \[2f(1-x)\,+f(x)=1+{{x}^{2}}-2x\]                              ...(ii) On multiplying Eq. (i) by 2 and subtracting from Eq. (ii), we get                 \[3f(x)={{x}^{2}}+2x-1\] \[\Rightarrow \]               \[f(x)=\frac{{{x}^{2}}+2x-1}{3}\]


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