JCECE Engineering JCECE Engineering Solved Paper-2003

  • question_answer
    The number that exceeds its square by the greatest number is:

    A) \[-1\]                                    

    B) \[0\]

    C)  \[\frac{1}{2}\]                                  

    D)  \[1\]

    Correct Answer: C

    Solution :

    Let the number be \[x\], then\[y=x-{{x}^{2}}\] On differentiating w.r.t. x, on both sides, we get                 \[\frac{dy}{dx}=1-2x\] For greatest or least number, put\[\frac{dy}{dx}=0\] \[\therefore \]  \[1-2x=0\Rightarrow x=\frac{1}{2}\] Again, differentiating, we get                 \[\frac{{{d}^{2}}y}{d{{x}^{2}}}=-2\]which is greatest \[\therefore \]  Greatest number is\[\frac{1}{2}\].


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