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    ​if ∑an\sum a_n∑an​ be an infinite series of non-negative terms and lim‾\overline{lim}lim an1/n=p{a_n^{1/n}} = pan1/n​=p, then ∑an\sum
    Question

    ​if an\sum a_n be an infinite series of non-negative terms and lim\overline{lim} an1/n=p{a_n^{1/n}} = p, then an\sum a_n is convegent if​

    A.

    p<1p<1​​

    B.

    p1p\leq 1​​

    C.

    p>1p>1​​

    D.

    p=1p=1​​

    Correct option is A

    Given:an is a series with non-negative terms, and liman1/n=pUsing Cauchy’s Root Test:Let L=lim supan1/n{L<1=>Series convergesL>1=>Series divergesL=1=>Test is inconclusiveSince liman1/n=p exists, we apply directly:p<1=>an convergesAnswer: (A) p<1\textbf{Given:}\\ \quad \sum a_n \text{ is a series with non-negative terms, and } \lim a_n^{1/n} = p \\[6pt]\textbf{Using Cauchy's Root Test:} \\\text{Let } L = \limsup a_n^{1/n} \\[4pt]\begin{cases}L < 1 & \Rightarrow \text{Series converges} \\L > 1 & \Rightarrow \text{Series diverges} \\L = 1 & \Rightarrow \text{Test is inconclusive}\end{cases} \\[10pt]\text{Since } \lim a_n^{1/n} = p \text{ exists, we apply directly:} \\p < 1 \Rightarrow \sum a_n \text{ converges} \\[10pt]\boxed{\text{Answer: (A) } p < 1}​​

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