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Category: Permutation and Combination

BeMath-1-find-1-2-2-0-pi-2-x-sin-x-1-cos-x-2-dx-

Question Number 108450 by bemath last updated on 17/Aug/20 $$\:\:\frac{\mathcal{B}{e}\mathcal{M}{ath}}{\subset\supset} \\ $$$$\left(\mathrm{1}\right){find}\:\left(\frac{\mathrm{1}}{\mathrm{2}}\right)! \\ $$$$\left(\mathrm{2}\right)\underset{\mathrm{0}} {\overset{\pi/\mathrm{2}} {\int}}\frac{{x}\:\mathrm{sin}\:{x}}{\left(\mathrm{1}+\mathrm{cos}\:{x}\right)^{\mathrm{2}} }\:{dx} \\ $$ Commented by Smail last updated on…

0-y-a-1-1-y-b-dy-u-1-1-y-0-1-1-u-a-1-u-a-1-u-b-du-u-2-0-1-u-b-a-1-1-u-a-1-du-

Question Number 173975 by savitar last updated on 22/Jul/22 $$ \\ $$$$\: \\ $$$$ \\ $$$$\:\:\:\:\:\int_{\mathrm{0}} ^{\infty} \frac{{y}^{{a}−\mathrm{1}} }{\left(\mathrm{1}+{y}\right)^{{b}} }\:{dy}\:\overset{{u}=\frac{\mathrm{1}}{\mathrm{1}+{y}}} {=}\:\:\:\int_{\mathrm{0}} ^{\mathrm{1}} \frac{\left(\mathrm{1}−{u}\right)^{{a}−\mathrm{1}} }{{u}^{{a}−\mathrm{1}} }\:{u}^{{b}}…

In-the-sequence-of-numbers-1-2-11-22-111-222-the-sum-of-the-digits-in-999th-terms-is-

Question Number 42494 by Tawa1 last updated on 26/Aug/18 $$\mathrm{In}\:\mathrm{the}\:\mathrm{sequence}\:\mathrm{of}\:\mathrm{numbers}\:\:\mathrm{1},\:\mathrm{2},\:\mathrm{11},\:\mathrm{22},\:\mathrm{111},\:\mathrm{222},\:…\:\mathrm{the}\:\mathrm{sum}\:\mathrm{of}\:\mathrm{the}\:\mathrm{digits} \\ $$$$\mathrm{in}\:\mathrm{999th}\:\mathrm{terms}\:\mathrm{is}\:?? \\ $$ Commented by Tinku Tara last updated on 22/Apr/21 $$\mathrm{1st}\:\mathrm{term}\:\mathrm{1} \\ $$$$\mathrm{3rd}\:\mathrm{term}\:\mathrm{11}…

A-general-case-we-have-totally-n-letters-among-them-n-1-times-A-n-2-times-B-n-3-times-C-n-4-times-D-etc-n-1-n-2-n-3-n-4-2-n-gt-n-1-n-2-n-3-n-4-how-many-different-words-

Question Number 107844 by mr W last updated on 13/Aug/20 $${A}\:{general}\:{case}: \\ $$$${we}\:{have}\:{totally}\:{n}\:{letters},\:{among}\:{them} \\ $$$${n}_{\mathrm{1}} \:{times}\:{A},\:{n}_{\mathrm{2}} \:{times}\:{B},\:{n}_{\mathrm{3}} \:{times}\:{C}, \\ $$$${n}_{\mathrm{4}} \:{times}\:{D}\:{etc}. \\ $$$$\left({n}_{\mathrm{1}} ,{n}_{\mathrm{2}} ,{n}_{\mathrm{3}}…

A-three-digit-odd-number-less-than-500-is-to-be-formed-from-1-2-3-4-and-5-If-repetition-of-digits-is-allowed-in-how-many-ways-can-this-be-done-

Question Number 173354 by pete last updated on 10/Jul/22 $$\mathrm{A}\:\mathrm{three}−\mathrm{digit}\:\mathrm{odd}\:\mathrm{number}\:\mathrm{less}\:\mathrm{than}\:\mathrm{500} \\ $$$$\mathrm{is}\:\mathrm{to}\:\mathrm{be}\:\mathrm{formed}\:\mathrm{from}\:\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{4}\:\mathrm{and}\:\mathrm{5}.\:\mathrm{If}\:\mathrm{repetition} \\ $$$$\mathrm{of}\:\mathrm{digits}\:\mathrm{is}\:\mathrm{allowed},\:\mathrm{in}\:\mathrm{how}\:\mathrm{many}\:\mathrm{ways} \\ $$$$\mathrm{can}\:\mathrm{this}\:\mathrm{be}\:\mathrm{done}? \\ $$ Commented by pete last updated on 10/Jul/22…