let-A-n-0-ne-x-dx-with-n-2-1-calculate-A-n-2-find-nature-of-n-2-A-n-3-study-the-convergence-of-1-A-n-and-1-A-n-2- Tinku Tara June 4, 2023 Relation and Functions 0 Comments FacebookTweetPin Question Number 41410 by maxmathsup by imad last updated on 06/Aug/18 letAn=∫0∞[ne−x]dxwithn⩾21)calculateAn2)findnatureof∑n⩾2An3)studytheconvergenceofΣ1AnandΣ1An2 Commented by maxmathsup by imad last updated on 07/Aug/18 1)changementne−x=tgivee−x=tn⇒ex=nt⇒x=ln(n)−ln(t)⇒dx=−dtt⇒An=−∫n0[t]dtt=∫0n[t]tdt=∑k=0n−1∫kk+1ktdt=∑k=0n−1k{ln(k+1)−ln(k)}=∑k=1n−1k{ln(k+1)−ln(k)}⇒An=∑k=1n−1kln(1+1k) Commented by maxmathsup by imad last updated on 07/Aug/18 2)wehaveln′(1+x)=11+x=1−x+x2−…if∣x∣<1⇒ln(1+x)=x−x22+x33−…⇒ln(1+x)⩾x−x22⇒ln(1+1k)⩾1k−12k2⇒∀k∈[[0,n−1]]kln(1+1k)⩾1−12k⇒∑k=1n−1kln(1+1k)⩾∑k=1n−1(1−12k)⇒An⩾n−1−12∑k=1n−11k⇒An⩾n−1−12Hn−1butHn−1=ln(n−1)+γ+o(1n)⇒n−1−12Hn−1=n−1−lnn−1−γ2+o(1n)butlimn→+∞n−1−lnn−1=+∞⇒An→+∞⇒ΣAndiverges Terms of Service Privacy Policy Contact: info@tinkutara.com FacebookTweetPin Post navigation Previous Previous post: Question-172483Next Next post: let-f-a-0-pi-dx-a-cos-2-x-with-a-gt-0-1-explicite-f-a-2-explicite-g-a-0-pi-dx-a-cos-2-x-2-3-find-tbe-valued-of-intevrsls-0-pi-dx-1-cos-2-x-and-0-pi-dx-1-cos-2-x- Leave a Reply Cancel replyYour email address will not be published. Required fields are marked *Comment * Name * Save my name, email, and website in this browser for the next time I comment.