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Category: Number Theory

Prove-that-every-even-number-can-be-expressed-as-sum-of-two-primes-or-give-an-counter-example-

Question Number 9049 by Rasheed Soomro last updated on 16/Nov/16 $$\mathrm{Prove}\:\mathrm{that}\:\mathrm{every}\:\mathrm{even}\:\mathrm{number}\:\mathrm{can}\:\mathrm{be}\: \\ $$$$\mathrm{expressed}\:\mathrm{as}\:\mathrm{sum}\:\mathrm{of}\:\mathrm{two}\:\mathrm{primes}\:\mathrm{or} \\ $$$$\mathrm{give}\:\mathrm{an}\:\mathrm{counter}\:\mathrm{example}. \\ $$ Commented by FilupSmith last updated on 16/Nov/16 $$\mathrm{2}{n}={p}_{\mathrm{1}}…

Determine-number-s-that-is-are-comprised-of-four-distinct-prime-factors-such-that-difference-of-largest-and-smallest-prime-factors-is-equal-to-the-sum-of-remaining-two-factors-Prop

Question Number 9025 by Rasheed Soomro last updated on 15/Nov/16 $$\mathrm{Determine}\:\mathrm{number}/\mathrm{s}\:\mathrm{that}\:\mathrm{is}/\mathrm{are}\:\mathrm{comprised} \\ $$$$\mathrm{of}\:\mathrm{four}\:\mathrm{distinct}\:\mathrm{prime}\:\mathrm{factors}\:\mathrm{such}\:\mathrm{that} \\ $$$$\mathrm{difference}\:\mathrm{of}\:\mathrm{largest}\:\mathrm{and}\:\mathrm{smallest}\:\mathrm{prime} \\ $$$$\mathrm{factors}\:\mathrm{is}\:\mathrm{equal}\:\mathrm{to}\:\mathrm{the}\:\mathrm{sum}\:\mathrm{of}\:\mathrm{remaining} \\ $$$$\mathrm{two}\:\mathrm{factors}.\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:_{\mathrm{Propsed}\:\mathrm{by}\:\mathrm{Rasheed}\:\mathrm{Soomro}} \\ $$ Commented by FilupSmith last…

What-is-the-remainder-when-13-5-14-5-15-5-16-5-is-divided-by-29-

Question Number 9021 by tawakalitu last updated on 14/Nov/16 $$\mathrm{What}\:\mathrm{is}\:\mathrm{the}\:\mathrm{remainder}\:\mathrm{when}\: \\ $$$$\left(\mathrm{13}^{\mathrm{5}} \:+\:\mathrm{14}^{\mathrm{5}} \:+\:\mathrm{15}^{\mathrm{5}} \:+\:\mathrm{16}^{\mathrm{5}} \right)\:\mathrm{is}\:\mathrm{divided}\:\mathrm{by}\:\mathrm{29}\:?\: \\ $$ Answered by aydnmustafa1976 last updated on 14/Nov/16…

Show-that-e-ipi-1-0-

Question Number 8838 by tawakalitu last updated on 31/Oct/16 $$\mathrm{Show}\:\mathrm{that}\::\:\:\mathrm{e}^{\mathrm{i}\pi\:+\:\mathrm{1}} \:=\:\mathrm{0} \\ $$ Answered by FilupSmith last updated on 31/Oct/16 $$\mathrm{do}\:\mathrm{you}\:\mathrm{mean}\:{e}^{{i}\pi} +\mathrm{1}=\mathrm{0} \\ $$$${e}^{{ix}} =\mathrm{cos}\left({x}\right)+{i}\mathrm{sin}\left({x}\right)…

Question-139668

Question Number 139668 by aupo14 last updated on 30/Apr/21 Commented by mr W last updated on 30/Apr/21 $${x}^{\mathrm{2}} \:{can}\:{only}\:{be}\:{formed}\:{from}\:{two}\:{times}\: \\ $$$$\left(\mathrm{1}+{x}+{x}^{\mathrm{3}} \right).\:{therefore}\:{the}\:{coefficient} \\ $$$${of}\:{x}^{\mathrm{2}} \:{is}\:{C}_{\mathrm{2}}…

n-1-2n-2-3n-3-rn-r-n-n-1-n-1-n-2-n-3-n-r-1-n-1-2-n-2-3-n-3-4-n-4-r-n-r-1-0-n-1-n-2-n-3-n-Prove-the-above-identity-

Question Number 139560 by Dwaipayan Shikari last updated on 28/Apr/21 $$\underset{{n}_{\mathrm{1}} +\mathrm{2}{n}_{\mathrm{2}} +\mathrm{3}{n}_{\mathrm{3}} +..+{rn}_{{r}} ={n}} {\overset{{n}} {\sum}}\frac{\mathrm{1}}{{n}_{\mathrm{1}} !{n}_{\mathrm{2}} !{n}_{\mathrm{3}} !..{n}_{{r}} !\mathrm{1}^{{n}_{\mathrm{1}} } \mathrm{2}^{{n}_{\mathrm{2}} } \mathrm{3}^{{n}_{\mathrm{3}}…

Determine-smallest-n-0-for-which-i-n-1-

Question Number 8336 by Rasheed Soomro last updated on 08/Oct/16 $$\mathrm{Determine}\:\mathrm{smallest}\:\mathrm{n}\left(\neq\mathrm{0}\right),\:\mathrm{for}\:\mathrm{which} \\ $$$$\left(\omega+\mathrm{i}\right)^{\mathrm{n}} =\mathrm{1}. \\ $$ Commented by prakash jain last updated on 08/Oct/16 $${w}=\mathrm{cos}\:\frac{\mathrm{2}\pi}{\mathrm{3}}+{i}\mathrm{sin}\:\frac{\mathrm{2}\pi}{\mathrm{3}}=−\frac{\mathrm{1}}{\mathrm{2}}+{i}\frac{\sqrt{\mathrm{3}}}{\mathrm{2}}…