CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2003

  • question_answer
    \[\underset{n\to \infty }{\mathop{\lim }}\,\,{{({{3}^{n}}+{{4}^{n}})}^{1/n}}\] is equal to :

    A)  4                                            

    B)  3

    C)  e                                           

    D)  \[\infty \]

    Correct Answer: A

    Solution :

    \[\underset{n\to \infty }{\mathop{\lim }}\,\,{{({{3}^{n}}+{{4}^{n}})}^{1/n}}\]                  \[\underset{n\to \infty }{\mathop{\lim }}\,{{\left[ {{4}^{n}}\left( \frac{{{3}^{n}}}{{{4}^{n}}}+1 \right) \right]}^{1/n}}\]                 \[=\underset{n\to \infty }{\mathop{\lim }}\,4{{\left[ {{\left( \frac{3}{4} \right)}^{n}}+1 \right]}^{1/n}}\]                 \[=4\,(0+1)\,\,\,\left[ \because \underset{n\to \infty }{\mathop{\lim }}\,\,\,{{r}^{n}}\to 0\,if\,r<1 \right]\]                 = 4


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