Category: Arithmetic

Question Number 93859 by  M±th+et+s last updated on 15/May/20 $$\underset{n=1}{\sum ^{\mathrm{\infty }}}\frac{1}{n(n+1)}$$ Answered by Ar Brandon last updated on 15/May/20 $$\frac{\mathrm{1}}{\mathrm{n}\left(\mathrm{n}+\mathrm{1}\right)}=\frac{\mathrm{1}}{\mathrm{n}}−\frac{\mathrm{1}}{\mathrm{n}+\mathrm{1}}\Rightarrow\underset{\mathrm{n}=\mathrm{1}} {\overset{\infty} {\sum}}\frac{\mathrm{1}}{\mathrm{n}\left(\mathrm{n}+\mathrm{1}\right)}=\underset{\mathrm{n}=\mathrm{1}}…

Question Number 93791 by peter frank last updated on 15/May/20 Commented by peter frank last updated on 15/May/20 $$iii$$ Terms of Service Privacy…

Question Number 159221 by physicstutes last updated on 14/Nov/21 $$\mathrm{find}\mathrm{the}\mathrm{general}\mathrm{term}\mathrm{of}$$$$\mathrm{the}\mathrm{sequence}$$$$3,5,9,17,33,\dots$$ Commented by MJS_new last updated on 14/Nov/21 $${a}_{{n}} =\frac{\mathrm{1}}{\mathrm{12}}{n}^{\mathrm{4}}…

Question Number 159184 by mathlove last updated on 14/Nov/21 Commented by som(math1967) last updated on 14/Nov/21 $$seeqno154258$$$$ans\frac{3}{8}$$ Commented by mathlove last…

Question Number 27908 by v7277668420 last updated on 16/Jan/18 $$IF{a}_{1,}{a}_2,\dots ..,a_{n-1},a_{n}areinAPthenprovethat$$$$\mathrm{1}/{a}_{\mathrm{1}} .{a}_{{n}} +\:\mathrm{1}/{a}_{\mathrm{2}} .{a}_{{n}−\mathrm{1}} +\:\mathrm{1}/{a}_{\mathrm{3}} .{a}_{{n}−\mathrm{2}} +…+\mathrm{1}/{a}_{{n}} .{a}_{\mathrm{1}} = \…