BCECE Engineering BCECE Engineering Solved Paper-2004

  • question_answer
    \[\int_{{}}^{{}}{{{5}^{{{5}^{{{5}^{x}}}}}}.}{{5}^{{{5}^{x}}}}{{.5}^{x}}dx\]is equal to:

    A) \[\frac{{{5}^{{{5}^{x}}}}}{{{(log5)}^{3}}}+c\]                        

    B)  \[{{5}^{{{5}^{{{5}^{x}}}}}}{{(log5)}^{3}}+c\]

    C)  \[\frac{{{5}^{{{5}^{{{5}^{x}}}}}}}{{{(log5)}^{3}}}+c\]        

    D)         none of  these

    Correct Answer: C

    Solution :

    Let \[I=\int_{{}}^{{}}{{{5}^{{{5}^{{{5}^{x}}}}}}{{.5}^{{{5}^{x}}}}{{.5}^{x}}dx}\] Put \[{{5}^{{{5}^{{{5}^{x}}}}}}=t\]\[\Rightarrow \]\[{{5}^{{{5}^{{{5}^{x}}}}}}{{.5}^{{{5}^{x}}}}{{.5}^{x}}{{(log5)}^{3}}dx=dt\] \[\therefore \]  \[I=\frac{1}{{{(log5)}^{3}}}\int_{{}}^{{}}{\frac{t\,dt}{t}}\]                 \[=\frac{t}{{{(log5)}^{3}}}+c\]                 \[=\frac{{{5}^{{{5}^{5}}^{x}}}}{{{(log5)}^{3}}}+c\]


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