Question Number 21756 by FilupS last updated on 03/Oct/17 $$\mathrm{Prove}\:\mathrm{that}\:\mathrm{the}\:\mathrm{product}\:\mathrm{for}\:\mathrm{all} \\ $$$${n}\mathrm{th}\:\mathrm{roots}\:\mathrm{of}\:\mathrm{unity}\:\mathrm{is}\:\mathrm{equal}\:\mathrm{to}\:\mathrm{zero}, \\ $$$$\mathrm{except}\:{n}=\mathrm{1}. \\ $$$$\: \\ $$$$\mathrm{Note}: \\ $$$${U}_{{n}} =\left\{{e}^{\mathrm{2}{k}\pi{i}/{n}} \:\mid\:{k}\in\left\{\mathrm{1},\:\mathrm{2},\:…,\:{n}\right\}\right\} \\ $$$${x}^{{n}} =\mathrm{1}…
Question Number 21682 by Tinkutara last updated on 30/Sep/17 $$\mathrm{Prove}\:\mathrm{that}\:\mathrm{the}\:\mathrm{ten}'\mathrm{s}\:\mathrm{digit}\:\mathrm{of}\:\mathrm{any}\:\mathrm{power} \\ $$$$\mathrm{of}\:\mathrm{3}\:\mathrm{is}\:\mathrm{even}.\:\left[\mathrm{e}.\mathrm{g}.\:\mathrm{the}\:\mathrm{ten}'\mathrm{s}\:\mathrm{digit}\:\mathrm{of}\:\mathrm{3}^{\mathrm{6}} \:=\right. \\ $$$$\left.\mathrm{729}\:\mathrm{is}\:\mathrm{2}\right]. \\ $$ Answered by alex041103 last updated on 30/Sep/17 $${We}\:{are}\:{going}\:{to}\:{prove}\:{this}\:{by}\:{induction}.…
Question Number 21573 by Tinkutara last updated on 27/Sep/17 $$\mathrm{Prove}\:\mathrm{that} \\ $$$$\mathrm{1}\:<\:\frac{\mathrm{1}}{\mathrm{1001}}\:+\:\frac{\mathrm{1}}{\mathrm{1002}}\:+\:\frac{\mathrm{1}}{\mathrm{1003}}\:+\:…\:+\:\frac{\mathrm{1}}{\mathrm{3001}}\:<\:\mathrm{1}\frac{\mathrm{1}}{\mathrm{3}}. \\ $$ Terms of Service Privacy Policy Contact: info@tinkutara.com
Question Number 21423 by Tinkutara last updated on 23/Sep/17 $$\mathrm{Prove}\:\mathrm{that}\:{n}^{\mathrm{4}} \:+\:\mathrm{4}^{{n}} \:\mathrm{is}\:\mathrm{composite}\:\mathrm{for}\:\mathrm{all} \\ $$$$\mathrm{integer}\:\mathrm{values}\:\mathrm{of}\:{n}\:\mathrm{greater}\:\mathrm{than}\:\mathrm{1}. \\ $$ Answered by dioph last updated on 24/Sep/17 $$\mathrm{If}\:{n}\:\mathrm{is}\:\mathrm{even},\:\mathrm{both}\:{n}^{\mathrm{4}} \:\mathrm{and}\:\mathrm{4}^{{n}}…
Question Number 21353 by Tinkutara last updated on 21/Sep/17 $$\mathrm{A}\:\mathrm{censusman}\:\mathrm{on}\:\mathrm{duty}\:\mathrm{visited}\:\mathrm{a}\:\mathrm{house} \\ $$$$\mathrm{which}\:\mathrm{the}\:\mathrm{lady}\:\mathrm{inmates}\:\mathrm{declined}\:\mathrm{to} \\ $$$$\mathrm{reveal}\:\mathrm{their}\:\mathrm{individual}\:\mathrm{ages},\:\mathrm{but}\:\mathrm{said}\:− \\ $$$$“\mathrm{we}\:\mathrm{do}\:\mathrm{not}\:\mathrm{mind}\:\mathrm{giving}\:\mathrm{you}\:\mathrm{the}\:\mathrm{sum}\:\mathrm{of} \\ $$$$\mathrm{the}\:\mathrm{ages}\:\mathrm{of}\:\mathrm{any}\:\mathrm{two}\:\mathrm{ladies}\:\mathrm{you}\:\mathrm{may} \\ $$$$\mathrm{choose}''.\:\mathrm{Thereupon}\:\mathrm{the}\:\mathrm{censusman} \\ $$$$\mathrm{said}\:−\:“\mathrm{In}\:\mathrm{that}\:\mathrm{case}\:\mathrm{please}\:\mathrm{give}\:\mathrm{me}\:\mathrm{the} \\ $$$$\mathrm{sum}\:\mathrm{of}\:\mathrm{the}\:\mathrm{ages}\:\mathrm{of}\:\mathrm{every}\:\mathrm{possible}\:\mathrm{pair}\:\mathrm{of} \\…
Question Number 21292 by FilupS last updated on 19/Sep/17 $$\mathrm{Let}\:\:{a},{b}\in\mathbb{Z} \\ $$$$\mathrm{0}<{a}<{b} \\ $$$$\: \\ $$$$\mathrm{How}\:\mathrm{would}\:\mathrm{you}\:\mathrm{find}\:\mathrm{the}\:\mathrm{maximum}/ \\ $$$$\mathrm{largest}\:\mathrm{prime}\:\mathrm{gap}\:\mathrm{in}\:\left({a},\:{b}\right)? \\ $$$$ \\ $$$$\mathrm{Note}: \\ $$$$\mathrm{Prime}\:\mathrm{gaps}\:\mathrm{are}\:\mathrm{the}\:\mathrm{distance}\:\mathrm{between} \\…
Question Number 21229 by Tinkutara last updated on 16/Sep/17 $$\mathrm{Let}\:{p},\:{q}\:\mathrm{be}\:\mathrm{prime}\:\mathrm{numbers}\:\mathrm{such}\:\mathrm{that} \\ $$$${n}^{\mathrm{3}{pq}} \:−\:{n}\:\mathrm{is}\:\mathrm{a}\:\mathrm{multiple}\:\mathrm{of}\:\mathrm{3}{pq}\:\mathrm{for}\:\boldsymbol{\mathrm{all}} \\ $$$$\mathrm{positive}\:\mathrm{integers}\:{n}.\:\mathrm{Find}\:\mathrm{the}\:\mathrm{least} \\ $$$$\mathrm{possible}\:\mathrm{value}\:\mathrm{of}\:{p}\:+\:{q}. \\ $$ Terms of Service Privacy Policy Contact:…
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Question Number 21031 by youssoufab last updated on 10/Sep/17 $${if}\::\forall\epsilon>\mathrm{0},\:\forall\left({a},{b}\right)\in\mathbb{R}^{\mathrm{2}} ,{a}<{b}+\epsilon \\ $$$${prove}:\:{a}\leqslant{b} \\ $$ Terms of Service Privacy Policy Contact: info@tinkutara.com
Question Number 86240 by Rio Michael last updated on 27/Mar/20 $$\mathrm{use}\:\mathrm{the}\:\mathrm{Chinese}\:\mathrm{Remainder}\:\mathrm{theorem}\:\mathrm{to}\:\mathrm{find} \\ $$$$\:\:{x}\:\mathrm{such}\:\mathrm{that} \\ $$$$\:{x}\:\equiv\:\mathrm{2}\left(\mathrm{mod}\:\mathrm{3}\right) \\ $$$$\mathrm{2}{x}\:\equiv\:\mathrm{3}\left(\mathrm{mod}\:\mathrm{5}\right) \\ $$$$\:\mathrm{3}{x}\equiv\:\mathrm{4}\left(\:\mathrm{mod}\:\mathrm{7}\right) \\ $$ Answered by mr W…