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Question Number 30758 by abdo imad last updated on 25/Feb/18
find lim_(n→∞) ((1/(n+1)) +(1/(n+2)) +....+(1/(n+p))) pfixed fromN^★
$${find}\:{lim}_{{n}\rightarrow\infty} \left(\frac{\mathrm{1}}{{n}+\mathrm{1}}\:+\frac{\mathrm{1}}{{n}+\mathrm{2}}\:+….+\frac{\mathrm{1}}{{n}+{p}}\right)\:{pfixed}\:{fromN}^{\bigstar} \\ $$$$ \\ $$
Commented by abdo imad last updated on 28/Feb/18
let put u_n =(1/(n+1)) +(1/(n+2)) +...+(1/(n+p))  u_n =H_(n+p)  −H_n =ln(n+p) +γ +o((1/n)) −ln(n) −γ −o^′ ((1/n))  =ln(((n+p)/n)) +o((1/n))_(n→∞) →0 ⇒ lim_(n→∞) u_n =0
$${let}\:{put}\:{u}_{{n}} =\frac{\mathrm{1}}{{n}+\mathrm{1}}\:+\frac{\mathrm{1}}{{n}+\mathrm{2}}\:+…+\frac{\mathrm{1}}{{n}+{p}} \\ $$$${u}_{{n}} ={H}_{{n}+{p}} \:−{H}_{{n}} ={ln}\left({n}+{p}\right)\:+\gamma\:+{o}\left(\frac{\mathrm{1}}{{n}}\right)\:−{ln}\left({n}\right)\:−\gamma\:−{o}^{'} \left(\frac{\mathrm{1}}{{n}}\right) \\ $$$$={ln}\left(\frac{{n}+{p}}{{n}}\right)\:+{o}\left(\frac{\mathrm{1}}{{n}}\right)_{{n}\rightarrow\infty} \rightarrow\mathrm{0}\:\Rightarrow\:{lim}_{{n}\rightarrow\infty} {u}_{{n}} =\mathrm{0} \\ $$

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