BCECE Engineering BCECE Engineering Solved Paper-2013

  • question_answer
    If the area above \[x-\]axis bounded by the n curves \[y={{2}^{Kx}},x=0\]and\[x=2\] is\[\frac{3}{\log 2},\]then  the value of K is

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

    B)                         1                            

    C)         \[-1\]                   

    D)                         2

    Correct Answer: B

    Solution :

    Area bounded by curves \[{{2}^{kx}}=y\]and \[x=0\]and \[x=2\]is given by \[A=\int\limits_{0}^{2}{{{2}^{kx}}dx}\] \[=\frac{1}{k}\left[ \frac{{{2}^{kx}}}{\log 2} \right]_{0}^{2}=\left[ \frac{{{2}^{2k}}-1}{k\log 2} \right]\]                 But         \[A=\frac{3}{\log 2}\]                 \[\therefore \]  \[\frac{{{2}^{2k}}-1}{k\,\log 2}=\frac{3}{\log 2}\]                                 \[{{2}^{2k}}-1=3k\] This relation is satisfied by only option (b).


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