JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{n\to \infty }{\mathop{\lim }}\,{{({{4}^{n}}+{{5}^{n}})}^{1/n}}\]is equal to

    A)                 \[4\]

    B)                 5

    C)                 \[e\]

    D)                 None of these

    Correct Answer: B

    Solution :

                       Given limit \[=\underset{n\to \infty }{\mathop{\lim }}\,\,{{({{4}^{n}}+{{5}^{n}})}^{1/n}}\]            \[=\underset{n\to \infty }{\mathop{\lim }}\,\,5\,{{\left[ {{\left\{ 1+{{\left( \frac{4}{5} \right)}^{n}} \right\}}^{{{(5/4)}^{n}}}} \right]}^{(1/n)\,.\,{{(4/5)}^{n}}}}=5\,.\,{{e}^{0}}=5\] . \[\left( \because \,\,{{\left( \frac{4}{5} \right)}^{n}}\to 0\,\text{as }\,n\to \infty  \right)\]


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