JEE Main & Advanced Mathematics Definite Integration Question Bank Fundamental definite integration, Definite integration by substitution

  • question_answer
    The value of \[\int_{0}^{2}{\frac{{{3}^{\sqrt{x}}}}{\sqrt{x}}}\,dx\] is                                        [SCRA 1992]

    A)                 \[\frac{2}{\log 3}.({{3}^{\sqrt{2}}}-1)\]  

    B)                 0

    C)                 \[2.\frac{\sqrt{2}}{\log 3}\]         

    D)                 \[\frac{{{3}^{\sqrt{2}}}}{\sqrt{2}}\]

    Correct Answer: A

    Solution :

               Put \[\sqrt{x}=t\]or \[\frac{1}{\sqrt{x}}dx=2\]dt            Also, as \[x=0\]to 2 so, \[t=0\]to \[\sqrt{2}\]            Therefore, \[\int_{0}^{2}{\frac{{{3}^{\sqrt{x}}}}{\sqrt{x}}\,}dx=2\int_{0}^{\sqrt{2}}{{{3}^{t}}}dt=2\left[ \frac{{{3}^{t}}}{\log 3} \right]_{0}^{\sqrt{2}}\]                                                       \[=\frac{2}{\log 3}({{3}^{\sqrt{2}}}-1)\].


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