BCECE Engineering BCECE Engineering Solved Paper-2014

  • question_answer
    On the interval [0,1], the function\[{{x}^{25}}{{(1-x)}^{75}}\] takes its maximum value at the point

    A) 0                                             

    B) \[\frac{1}{4}\]

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

    D) \[\frac{1}{3}\]

    Correct Answer: B

    Solution :

    Let \[f(x)={{x}^{25}}{{(1-x)}^{75}}\] On differentiating w. r. t. x,  we get \[f'(x)=25{{x}^{24}}{{(1-x)}^{75}}-75{{x}^{25}}{{(1-x)}^{74}}\] \[=25{{x}^{24}}[{{(1-x)}^{74}}(1-x-3x)]\] \[=25{{x}^{24}}{{(1-x)}^{74}}(1-4x)\] \[\therefore \]  \[f'(x)\] changes sign about \[x=\frac{1}{4}\] only.


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