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Author: Tinku Tara

Find-n-1-1-n-2n-1-2-

Question Number 226509 by hardmath last updated on 01/Dec/25 $$\mathrm{Find}:\:\:\:\underset{\boldsymbol{\mathrm{n}}=\mathrm{1}} {\overset{\infty} {\sum}}\:\frac{\mathrm{1}}{\mathrm{n}\centerdot\left(\mathrm{2n}\:+\:\mathrm{1}\right)^{\mathrm{2}} }\:=\:? \\ $$ Answered by mr W last updated on 01/Dec/25 $$\frac{\mathrm{1}}{{n}\left(\mathrm{2}{n}+\mathrm{1}\right)^{\mathrm{2}} }=\frac{{A}}{{n}}+\frac{{B}}{\mathrm{2}{n}+\mathrm{1}}+\frac{{C}}{\left(\mathrm{2}{n}+\mathrm{1}\right)^{\mathrm{2}}…

Question-226507

Question Number 226507 by Lara2440 last updated on 01/Dec/25 Answered by Lara2440 last updated on 01/Dec/25 $$\mathrm{Smooth}\:\mathrm{manifold}\:{M},{N}\:\mathrm{and} \\ $$$$\mathrm{Differentiable}\:\mathrm{smooth}\:\mathrm{function}\:\:\phi;{M}\rightarrow{N} \\ $$$$\: \\ $$$$\phi\left({u},{v}\right)=\begin{cases}{−\mathrm{sin}\left({u}\right)−\mathrm{3sin}\left({v}\right)}\\{\:\:\:\:\mathrm{cos}\left({u}\right)+\mathrm{3cos}\left({v}\right)\:\:\:\:\:\:,\:{u}\in\left[−\pi,\pi\right]\:,\:{v}\in\left[−\mathrm{2}\pi,\mathrm{2}\pi\right]}\\{\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\mathrm{5}{v}}\end{cases} \\ $$$$\:…

Question-226515

Question Number 226515 by mr W last updated on 01/Dec/25 Commented by Ghisom_ last updated on 02/Dec/25 $${S}_{{k}} =\underset{{n}=\mathrm{1}} {\overset{{k}} {\sum}}\:\frac{{n}}{{n}^{\mathrm{4}} +{n}^{\mathrm{2}} +\mathrm{1}}\:=\frac{{k}\left({k}+\mathrm{1}\right)}{\mathrm{2}\left({k}^{\mathrm{2}} +{k}+\mathrm{1}\right)} \\…