JCECE Engineering JCECE Engineering Solved Paper-2004

  • question_answer
    The minimum value of \[{{x}^{2}}+\frac{1}{1+{{x}^{2}}}\] is at:

    A) \[x=0\]                

    B) \[x=4\]

    C) \[x=1\]                                

    D) \[x=3\]

    Correct Answer: A

    Solution :

    Let\[f(x)={{x}^{2}}+\frac{1}{1+{{x}^{2}}}\] On differentiating w.r.t.\[x,\] we get                 \[f'(x)=2x-\frac{1}{{{(1+{{x}^{2}})}^{2}}}(2x)\] For maxima or minima, put\[f'(x)=0\] \[\therefore \]  \[2x-\frac{2x}{{{(1+{{x}^{2}})}^{2}}}=0\] \[\Rightarrow \]               \[2x\left[ 1-\frac{1}{{{(1+{{x}^{2}})}^{2}}} \right]=0\] \[\Rightarrow \]               \[x=0\] \[\therefore \] The minimum value at\[x=0\].


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