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Category: Arithmetic

Evaluate-1-1-2-3-3-2-3-4-5-3-4-5-2n-1-n-n-1-n-2-

Question Number 103648 by Lordose last updated on 16/Jul/20 $$\boldsymbol{\mathrm{Evaluate}}\:\frac{\mathrm{1}}{\mathrm{1}\centerdot\mathrm{2}\centerdot\mathrm{3}}+\frac{\mathrm{3}}{\mathrm{2}\centerdot\mathrm{3}\centerdot\mathrm{4}}+\frac{\mathrm{5}}{\mathrm{3}\centerdot\mathrm{4}\centerdot\mathrm{5}}+…+\frac{\mathrm{2}\boldsymbol{\mathrm{n}}−\mathrm{1}}{\boldsymbol{\mathrm{n}}\left(\boldsymbol{\mathrm{n}}+\mathrm{1}\right)\left(\boldsymbol{\mathrm{n}}+\mathrm{2}\right.} \\ $$ Answered by Dwaipayan Shikari last updated on 16/Jul/20 $${T}_{{n}} =\frac{\mathrm{2}{n}−\mathrm{1}}{{n}\left({n}+\mathrm{1}\right)\left({n}+\mathrm{2}\right)} \\ $$$$\Sigma{T}_{{n}} =\Sigma\frac{{n}+{n}+\mathrm{2}−\mathrm{3}}{{n}\left({n}+\mathrm{1}\right)\left({n}+\mathrm{2}\right)}=\Sigma\frac{\mathrm{1}}{{n}\left({n}+\mathrm{1}\right)}+\Sigma\frac{\mathrm{1}}{\left({n}+\mathrm{1}\right)\left({n}+\mathrm{2}\right)}−\frac{\mathrm{3}}{\mathrm{2}}\Sigma\frac{\mathrm{2}+{n}−{n}}{{n}\left({n}+\mathrm{1}\right)\left({n}+\mathrm{2}\right)}…

The-question-is-n-1-2n-1-n-n-1-n-2-

Question Number 103633 by Lordose last updated on 16/Jul/20 $$ \\ $$$$\boldsymbol{\mathrm{The}}\:\boldsymbol{\mathrm{question}}\:\boldsymbol{\mathrm{is}} \\ $$$$\underset{\boldsymbol{\mathrm{n}}=\mathrm{1}} {\overset{\infty} {\sum}}\left(\frac{\mathrm{2}\boldsymbol{\mathrm{n}}−\mathrm{1}}{\boldsymbol{\mathrm{n}}\left(\boldsymbol{\mathrm{n}}+\mathrm{1}\right)\left(\boldsymbol{\mathrm{n}}+\mathrm{2}\right.}\right)=… \\ $$ Commented by bobhans last updated on 16/Jul/20…

find-the-sum-of-the-series-whose-nth-term-is-2n-1-n-n-1-n-2-i-have-a-problem-with-this-and-i-need-help-please-

Question Number 103623 by Lordose last updated on 16/Jul/20 $$\boldsymbol{\mathrm{find}}\:\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{sum}}\:\boldsymbol{\mathrm{of}}\:\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{series}}\:\boldsymbol{\mathrm{whose}}\:\boldsymbol{\mathrm{nth}} \\ $$$$\boldsymbol{\mathrm{term}}\:\boldsymbol{\mathrm{is}}\:\frac{\mathrm{2}\boldsymbol{\mathrm{n}}−\mathrm{1}}{\boldsymbol{\mathrm{n}}\left(\boldsymbol{\mathrm{n}}+\mathrm{1}\right)\left(\boldsymbol{\mathrm{n}}+\mathrm{2}\right.}. \\ $$$$\boldsymbol{\mathrm{i}}\:\boldsymbol{\mathrm{have}}\:\boldsymbol{\mathrm{a}}\:\boldsymbol{\mathrm{problem}}\:\boldsymbol{\mathrm{with}}\:\boldsymbol{\mathrm{this}}\:\boldsymbol{\mathrm{and}}\:\boldsymbol{\mathrm{i}}\:\boldsymbol{\mathrm{need}} \\ $$$$\boldsymbol{\mathrm{help}}\:\boldsymbol{\mathrm{please}} \\ $$ Answered by OlafThorendsen last updated on 16/Jul/20…

5-5-5-5-5-5-5-

Question Number 103321 by bemath last updated on 14/Jul/20 $$\mathrm{5}+\sqrt{\mathrm{5}−\sqrt{\mathrm{5}+\sqrt{\mathrm{5}−\sqrt{\mathrm{5}+\sqrt{\mathrm{5}−\sqrt{\mathrm{5}+…}}}}}} \\ $$ Answered by Dwaipayan Shikari last updated on 14/Jul/20 $$\sqrt{\mathrm{5}−\sqrt{\mathrm{5}+\sqrt{\mathrm{5}…}}}={p} \\ $$$$\mathrm{5}−\sqrt{\mathrm{5}+\sqrt{\mathrm{5}−\sqrt{\mathrm{5}}}}…={p}^{\mathrm{2}} \\ $$$$\mathrm{5}+{p}=\left(\mathrm{5}−{p}^{\mathrm{2}}…

Evaluate-r-0-2-r-1-

Question Number 37712 by Rio Mike last updated on 16/Jun/18 $${Evaluate}\:\underset{{r}=\mathrm{0}} {\overset{\infty} {\sum}}\mathrm{2}^{{r}−\mathrm{1}} \\ $$ Commented by prakash jain last updated on 17/Jun/18 $$−\mathrm{1}/\mathrm{2}\:\mathrm{is}\:\mathrm{also}\:\mathrm{a}\:\mathrm{valid}\:\mathrm{answer}\:\mathrm{using} \\…

3-3-3-3-1-or-3-3-3-3-3-

Question Number 168391 by Florian last updated on 09/Apr/22 $$\:\:\:\frac{\mathrm{3}\sqrt{\mathrm{3}}}{\mathrm{3}\sqrt{\mathrm{3}}}=\mathrm{1}\:\:\:\:{or}\:\:\mathrm{3}×\sqrt{\mathrm{3}}\boldsymbol{\div}\mathrm{3}×\sqrt{\mathrm{3}}\:=\mathrm{3}\:\:\:\:\:\:\:\:\:\:\:??? \\ $$ Commented by Rasheed.Sindhi last updated on 09/Apr/22 $$\:\frac{\mathrm{3}\sqrt{\mathrm{3}}}{\mathrm{3}\sqrt{\mathrm{3}}}=\left(\mathrm{3}×\sqrt{\mathrm{3}}\:\right)\boldsymbol{\div}\left(\mathrm{3}×\sqrt{\mathrm{3}}\:\right) \\ $$$$\mathrm{Where}\:\mathrm{as} \\ $$$$\mathrm{3}×\sqrt{\mathrm{3}}\boldsymbol{\div}\mathrm{3}×\sqrt{\mathrm{3}}\:=\mathrm{3}×\left(\sqrt{\mathrm{3}}\boldsymbol{\div}\mathrm{3}\right)×\sqrt{\mathrm{3}} \\…