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Category: Permutation and Combination

say-you-have-3-different-books-about-mathematics-4-different-books-about-physics-and-5-different-books-about-chemistry-in-how-many-ways-can-you-arrange-them-in-a-shelf-such-that-no-two-books-f

Question Number 196143 by mr W last updated on 18/Aug/23 $${say}\:{you}\:{have}\:\mathrm{3}\:\left({different}\right)\:{books} \\ $$$${about}\:{mathematics},\:\mathrm{4}\:\left({different}\right) \\ $$$${books}\:{about}\:{physics}\:{and}\:\mathrm{5}\:\left({different}\right) \\ $$$${books}\:{about}\:{chemistry}.\:{in}\:{how}\:{many} \\ $$$${ways}\:{can}\:{you}\:{arrange}\:{them}\:{in}\:{a}\:{shelf} \\ $$$${such}\:{that}\:{no}\:{two}\:{books}\:{from}\:{the}\:{same} \\ $$$${subject}\:{are}\:{adjacent}? \\ $$…

the-family-A-has-5-members-and-the-family-B-has-4-members-there-are-6-personsfrom-other-families-in-how-many-ways-can-you-arrange-these-15-persons-around-a-round-table-such-that-no-member-from-fami

Question Number 195964 by mr W last updated on 15/Aug/23 $${the}\:{family}\:{A}\:{has}\:\mathrm{5}\:{members}\:{and}\:{the} \\ $$$${family}\:{B}\:{has}\:\mathrm{4}\:{members}.\:{there}\:{are}\: \\ $$$$\mathrm{6}\:{personsfrom}\:{other}\:{families}. \\ $$$${in}\:{how}\:{many}\:{ways}\:{can}\:{you}\:{arrange} \\ $$$${these}\:\mathrm{15}\:{persons}\:{around}\:{a}\:{round}\:{table} \\ $$$${such}\:{that}\:{no}\:{member}\:{from}\:{family}\:{A} \\ $$$${and}\:{no}\:{member}\:{from}\:{family}\:{B}\:{are} \\ $$$${next}\:{to}\:{each}\:{other}?…

how-many-different-words-can-be-formed-from-the-letters-in-aaacdefgbbbb-such-that-a-a-and-a-b-are-not-next-to-each-other-see-also-Q-195606-

Question Number 195672 by mr W last updated on 07/Aug/23 $${how}\:{many}\:{different}\:{words}\:{can}\:{be} \\ $$$${formed}\:{from}\:{the}\:{letters}\:{in} \\ $$$$\boldsymbol{{aaacdefgbbbb}} \\ $$$${such}\:{that}\:{a}\:“\boldsymbol{{a}}''\:{and}\:{a}\:“\boldsymbol{{b}}''\:{are}\:{not} \\ $$$${next}\:{to}\:{each}\:{other}? \\ $$$$ \\ $$$$\left({see}\:{also}\:{Q}#\mathrm{195606}\right) \\ $$…

sequence-of-string-said-to-be-orderly-if-element-index-i-different-to-i-1-for-example-aba-has-orderly-value-2-abab-has-orderly-value-3-abaabb-has-orderly-value-3-if-there-are-7-a-and-13-b-exa

Question Number 195666 by uchihayahia last updated on 07/Aug/23 $$ \\ $$$$\:{sequence}\:{of}\:{string}\:{said}\:{to}\:{be}\:{orderly} \\ $$$$\:{if}\:{element}\:{index}\:{i}\:{different}\:{to}\:{i}+\mathrm{1} \\ $$$$\:{for}\:{example} \\ $$$$\:{aba}\:{has}\:{orderly}\:{value}\:\mathrm{2} \\ $$$$\:{abab}\:{has}\:{orderly}\:{value}\:\mathrm{3} \\ $$$$\:{abaabb}\:{has}\:{orderly}\:{value}\:\mathrm{3} \\ $$$$\:{if}\:{there}\:{are}\:\mathrm{7}\:{a}\:{and}\:\mathrm{13}\:{b} \\…

Number-of-distributions-of-n-different-articles-to-r-different-boxes-so-as-1-empty-box-allowed-2-empty-box-not-allowed-with-proof-kindly-help-me-

Question Number 195538 by SLVR last updated on 04/Aug/23 $${Number}\:{of}\:{distributions}\:{of} \\ $$$${n}\:{different}\:{articles}\:{to}\:{r}\:{different}\:\:{boxes} \\ $$$$\left.{so}\:{as}\:\mathrm{1}\right){empty}\:{box}\:{allowed} \\ $$$$\left.\mathrm{2}\right){empty}\:{box}\:{not}\:{allowed} \\ $$$${with}\:{proof}…{kindly}\:{help}\:{me} \\ $$ Commented by SLVR last updated…

Calculer-lim-x-0-sin-x-2-n-1-2-n-sinx-cos-x-2-n-sin-2-x-2-n-

Question Number 195191 by Erico last updated on 26/Jul/23 $$\mathrm{Calculer}\underset{\mathrm{x}\rightarrow\mathrm{0}} {\:\mathrm{lim}}\frac{\mathrm{sin}\left(\frac{\mathrm{x}}{\mathrm{2}^{\mathrm{n}} }\right)−\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{n}} }\mathrm{sinx}\:\mathrm{cos}\left(\frac{\mathrm{x}}{\mathrm{2}^{\mathrm{n}} }\right)}{\mathrm{sin}^{\mathrm{2}} \left(\frac{\mathrm{x}}{\mathrm{2}^{\mathrm{n}} }\right)} \\ $$ Terms of Service Privacy Policy Contact: info@tinkutara.com

Soit-x-gt-1-On-de-finie-la-suite-p-n-par-p-1-x-et-n-IN-p-n-1-2p-n-2-1-Montrer-que-lim-n-k-1-n-1-1-p-k-x-1-x-1-

Question Number 194960 by Erico last updated on 20/Jul/23 $$\mathrm{Soit}\:{x}>\mathrm{1}.\:\mathrm{On}\:\mathrm{d}\acute {\mathrm{e}finie}\:\mathrm{la}\:\mathrm{suite}\:\left(\mathrm{p}_{\mathrm{n}} \right)\:\mathrm{par}\: \\ $$$$\mathrm{p}_{\mathrm{1}} ={x}\:\:\mathrm{et}\:\forall\mathrm{n}\in\mathrm{IN}^{\ast} \:\:\:\:\:\mathrm{p}_{\mathrm{n}+\mathrm{1}} =\mathrm{2p}_{\mathrm{n}} ^{\mathrm{2}} −\mathrm{1} \\ $$$$\mathrm{Montrer}\:\mathrm{que}\:\underset{\mathrm{n}\rightarrow+\infty} {\mathrm{lim}}\:\underset{\mathrm{k}=\mathrm{1}} {\overset{\mathrm{n}} {\prod}}\left(\mathrm{1}+\frac{\mathrm{1}}{\mathrm{p}_{\mathrm{k}} }\right)=\sqrt{\frac{{x}+\mathrm{1}}{{x}−\mathrm{1}}}…

Prove-that-n-IN-k-1-2-n-1-1-sin-2-kpi-2-n-1-2-2n-1-2-3-Give-in-terms-of-n-k-1-2-n-1-1-sin-4-kpi-2-n-1-

Question Number 194638 by Erico last updated on 12/Jul/23 $$\mathrm{Prove}\:\mathrm{that}\:\forall{n}\in\mathrm{IN}^{\ast} \:\:\:\:\: \\ $$$$\:\:\:\underset{{k}=\mathrm{1}} {\overset{\mathrm{2}^{{n}} −\mathrm{1}} {\sum}}\:\frac{\mathrm{1}}{{sin}^{\mathrm{2}} \left(\frac{{k}\pi}{\mathrm{2}^{{n}+\mathrm{1}} }\right)}=\:\frac{\mathrm{2}^{\mathrm{2}{n}+\mathrm{1}} −\mathrm{2}}{\mathrm{3}} \\ $$$$\mathrm{Give}\:\mathrm{in}\:\mathrm{terms}\:\mathrm{of}\:{n}\:\:\:\underset{{k}=\mathrm{1}} {\overset{\mathrm{2}^{{n}} −\mathrm{1}} {\sum}}\:\frac{\mathrm{1}}{{sin}^{\mathrm{4}} \left(\frac{{k}\pi}{\mathrm{2}^{{n}+\mathrm{1}}…