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Diferencial v matematici golovna linijna vidnosno prirostu argumentu chastina prirostu funkciyi abo vidobrazhennya V matematichnomu analizi diferencial tradicijno vvazhayetsya neskinchenno malim prirostom zminnoyi Napriklad yaksho x zminna todi pririst znachennya x chasto poznachayetsya Dx chi dx yaksho cej pririst malij Diferencial dx takozh ye takim prirostom ale neskinchenno malim Varto zaznachiti sho take viznachennya ne ye matematichno strogim ale vono zruchne dlya rozuminnya takozh isnuye bagato sposobiv zrobiti viznachennya matematichno tochnishim Pririst ta linijna chastina prirostu funkciyi odniyeyi zminnoyiGolovna vlastivist diferencialu yaksho y funkciya vid x todi diferencial dy vid y pov yazanij z dx formuloyu d y d y d x d x displaystyle mathrm d y frac mathrm d y mathrm d x mathrm d x de dy dx poznachaye pohidnu vid y po zminnij x Cya formula pidsumovuye intuyitivne tverdzhennya sho pohidna y po zminnij x ce granicya vidnoshennya prirostiv Dy Dx de Dx pryamuye do nulya Diferencial yak linijne vidobrazhennya Cej pidhid ye osnovoyu viznachennya povnoyi pohidnoyi i zovnishnoyi pohidnoyi v diferencialnij geometriyi 1 Diferencial yak nilpotentnij element v komutativnih kilcyah Takij pidhid populyarnij v algebrayichnij geometriyi 2 Ci pidhodi duzhe rizni ale yih ob yednuye ideya kilkisnogo tobto vazhlivo skazati sho diferencial ne tilki neskinchenno malij a naskilki same vin malij Zmist 1 Istoriya i vikoristannya 2 Formalni oznachennya 2 1 Vipadok odniyeyi zminnoyi 2 2 Vipadok bagatoh zminnih 2 3 Vidobrazhennya mizh evklidovimi prostorami 2 4 Vidobrazhennya mizh mnogovidami 3 Dzherela 4 PrimitkiIstoriya i vikoristannya RedaguvatiNeskinchenno mali velichini grali znachnu rol v rozvitku matematichnogo analizu Arhimed vikoristovuvav yih hocha vin i ne viriv sho tverdzhennya z neskinchenno malimi velichinami mozhut buti tochni 3 Bhaskara II rozrobiv koncepciyu diferencialnogo vidobrazhennya neskinchenno malih zmin 4 Sharaf al Din al Tusi vikoristovuvav yih dlya obchislennya pohidnoyi kubichnogo rivnyannya 5 6 Isaak Nyuton nazivav yih pohidnimi Prote Lejbnic buv pershij hto zastosuvav termin diferencial do neskinchenno malih velichin a takozh pridumav poznachennya pohidnoyi yake vikoristovuyetsya doteper V poznachenni Lejbnica yaksho x zminne chislo todi dx poznachaye neskinchenno malij pririst zminnoyi x Takim chinom yaksho y funkciya vid x todi pohidna y po zminnij x chasto poznachayetsya d y d x displaystyle frac mathrm d y mathrm d x nbsp sho takozh mozhe buti zapisano poznachennya Nyutona chi Lagranzha y x displaystyle dot y x nbsp chi y x displaystyle y x nbsp Vikoristannya diferencialiv v takij formi sprovokuvalo bagato kritiki napriklad znamenitij pamflet The Analyst yepiskopa Berkli V bud yakomu razi take poznachennya zalishilos populyarnim tomu sho vono naochno vidobrazhaye princip sho pohidna funkciyi y x dorivnyuye nahilu funkciyi v tochci sho mozhna otrimati yaksho obchisliti granicyu vidnoshennya D y D x displaystyle frac Delta y Delta x nbsp prirostu y v zalezhnosti vid prirostu x yaksho pririst x pryamuye do nulya Diferenciali takozh zastosovuyut v analizi rozmirnosti de diferencial napriklad dx mayu taku samu rozmirnist yak i zminna x Suma Rimana ye pevnogo vidu nablizhennyam integralu za dopomogoyu skinchennoyi sumi Vona nazvana na chest nimeckogo matematika iz dev yatnadcyatogo stolittya Berngarda Rimana Jogo odnim iz samih zagalnih zastosuvan ye aproksimaciya ploshi sho obmezhuyut grafiki funkcij abo krivi a takozh dovzhini krivih i inshi nablizhennya Diferencial vikoristovuyut v poznachenni integrala tomu sho integral mozhna vvazhati neskinchennoyu sumoyu neskinchenno malih velichin plosha pid grafikom funkciyi obchislyuyetsya yak suma plosh neskinchenno tonkih strichok U virazi f x d x displaystyle int f x mathrm d x nbsp znak integrala vityagnute s oznachaye neskinchennu sumu f x poznachaye visotu tonkoyi strichki a diferencial dx poznachaye neskinchenno tonku shirinu Formalni oznachennya RedaguvatiOb yem kuba funkciya vid dovzhini jogo storoni V x 3 displaystyle V x 3 nbsp Za rahunok linijnogo termichnogo rozshirennya storoni kuba zbilshuyutsya a tomu zbilshuyetsya i jogo ob yem Yaksho dovzhina storoni kuba mala znachennya x displaystyle x nbsp i zbilshilasya na h displaystyle h nbsp to vona prijme znachennya x h displaystyle x h nbsp i ob yem kuba stane rivnim x h 3 displaystyle x h 3 nbsp Velichina na yaku zbilshitsya jogo ob yem bude skladati x h 3 x 3 displaystyle x h 3 x 3 nbsp Cyu riznicyu nazivayut priroshennyam ob yemu kuba a chislo h displaystyle h nbsp yake pokazuye na skilki zbilshilasya dovzhina storoni kuba nazivayetsya priroshennyam jogo dovzhini U matematici priroshennya yakoyi nebud velichini poznachayetsya D x displaystyle Delta x nbsp de D displaystyle Delta nbsp velika grecka litera delta yaka nagaduye pro latinske slovo differentia riznicya nbsp Yaksho funkciya y f x displaystyle y f x nbsp zrostaye na vidrizku a b displaystyle a b nbsp to na comu vidrizku znaki D y displaystyle Delta y nbsp ta D x displaystyle Delta x nbsp spivpadayut pri zbilshenni x displaystyle x nbsp zbilshuyetsya j y displaystyle y nbsp a pri zmenshenni x displaystyle x nbsp zmenshuyetsya j y displaystyle y nbsp grafik livoruch na malyunku Yaksho zh funkciya y f x displaystyle y f x nbsp spadaye na comu vidrizku to u bud yakij jogo tochci znaki D x displaystyle Delta x nbsp ta D y displaystyle Delta y nbsp protilezhni Yaksho y f x displaystyle y f x nbsp deyaka funkciya j x displaystyle x nbsp priroshuyetsya D x displaystyle Delta x nbsp to zminyuyetsya j znachennya funkciyi v rezultati chogo vona otrimuye deyake priroshennya D y displaystyle Delta y nbsp Shob obchisliti ce priroshennya neobhidno znajti znachennya funkciyi pri pochatkovomu znachenni argumenta tobto y f x displaystyle y f x nbsp znajti nove znachennya argumenta tobto x D x displaystyle x Delta x nbsp znajti nove znachennya funkciyi tobto f x D x displaystyle f x Delta x nbsp z novogo znachennya funkciyi vidnyati pochatkove yiyi znachennya tobto D y f x D x f x displaystyle Delta y f x Delta x f x nbsp Napriklad priroshennya funkciyi y x 3 displaystyle y x 3 nbsp maye viglyad D y 3 x 2 D x 3 x D x 2 D x 3 displaystyle Delta y 3x 2 Delta x 3x Delta x 2 Delta x 3 nbsp ce priroshennya mozhna zapisati nastupnim chinom D y 3 x 2 D x 3 x D x D x 2 D x displaystyle Delta y 3x 2 Delta x 3x Delta x Delta x 2 Delta x nbsp Vono skladayetsya z dvoh dodankiv 3 x 2 D x displaystyle 3x 2 Delta x nbsp ta 3 x D x D x 2 D x displaystyle 3x Delta x Delta x 2 Delta x nbsp Pershij dodanok proporcijnij priroshennyu argumentu D x displaystyle Delta x nbsp Drugij dodanok skladnishij zalezhit vid D x displaystyle Delta x nbsp Ale za malih D x displaystyle Delta x nbsp vin nabagato menshij nizh 3 x 2 D x displaystyle 3x 2 Delta x nbsp tomu sho ye dobutkom D x displaystyle Delta x nbsp na viraz 3 x D x D x 2 displaystyle 3x Delta x Delta x 2 nbsp yakij pryamuye do nulya za D x 0 displaystyle Delta x to 0 nbsp x 1 displaystyle x 1 nbsp D x displaystyle Delta x nbsp D y displaystyle Delta y nbsp 3 x 2 D x displaystyle 3x 2 Delta x nbsp 3 x D x D x 2 D x displaystyle 3x Delta x Delta x 2 Delta x nbsp 0 1 0 331 0 3 0 0310 01 0 030301 0 03 0 0003010 001 0 003003001 0 003 0 000003001Takim chinom dodanok 3 x 2 D x displaystyle 3x 2 Delta x nbsp yakij ye proporcijnim D x displaystyle Delta x nbsp za malih znachen D x displaystyle Delta x nbsp ye golovnoyu chastinoyu priroshennya funkciyi Takij dodanok nazivayetsya diferencialom j poznachayetsya d y 3 x 2 D x displaystyle dy 3x 2 Delta x nbsp Vin zalezhit ne lishe vid D x displaystyle Delta x nbsp ale j vid x displaystyle x nbsp Napriklad dlya funkciyi y x 3 displaystyle y x 3 nbsp pri x 1 displaystyle x 1 nbsp ta D x 0 1 displaystyle Delta x 0 1 nbsp vin dorivnyuye d y 1 2 displaystyle dy 1 2 nbsp U vipadku D x 0 01 displaystyle Delta x 0 01 nbsp ta x 1 displaystyle x 1 nbsp diferencial d y 0 03 displaystyle dy 0 03 nbsp nbsp Diferencial funkciyi S x 2 displaystyle S x 2 nbsp Priroshennya funkciyi y x 2 displaystyle y x 2 nbsp maye viglyad D y x D x 2 x 2 2 x D x D x 2 displaystyle Delta y x Delta x 2 x 2 2x Delta x Delta x 2 nbsp Dodankom proporcijnim D x displaystyle Delta x nbsp ye 2 x D x displaystyle 2x Delta x nbsp Cej dodanok i ye diferencialom zadanoyi funkciyi d y 2 x D x 2 x d x displaystyle dy 2x Delta x 2x dx nbsp Formula dlya diferencialu y x 2 displaystyle y x 2 nbsp maye prostij geometrichnij sens Oskilki S x 2 displaystyle S x 2 nbsp ploshina kvadrata storona yakogo maye dovzhinu x displaystyle x nbsp to D S displaystyle Delta S nbsp ploshina figuri na yaku yiyi plosha zbilshuyetsya Zrozumilo sho za malih D x displaystyle Delta x nbsp golovnu chastinu ciyeyi ploshini skladaye ploshina dvoh pryamokutnikiv yaka dorivnyuye 2 x D x displaystyle 2x Delta x nbsp tobto diferencialu funkciyi S x 2 displaystyle S x 2 nbsp Viraz D x 2 displaystyle Delta x 2 nbsp ploshina kvadratika yaka neskinchenno mala u porivnyanni iz D x displaystyle Delta x nbsp Vipadok odniyeyi zminnoyi Redaguvati Nehaj v okoli tochki x 0 displaystyle x 0 nbsp zadana funkciya f x X Y displaystyle f x X rightarrow Y nbsp nehaj isnuye take A displaystyle A nbsp sho f x f x 0 A x x 0 o x x 0 displaystyle f x f x 0 A x x 0 o x x 0 nbsp pri x x 0 displaystyle x rightarrow x 0 nbsp Poznachimo x x 0 d x displaystyle x x 0 dx nbsp Todi funkciya d f A d x displaystyle df Adx nbsp nazivayetsya diferencialom funkciyi f x displaystyle f x nbsp v tochci x 0 displaystyle x 0 nbsp Vipadok bagatoh zminnih Redaguvati Priklad 1 Nehaj v okoli tochki x 0 x 0 1 x 0 2 x 0 n displaystyle overrightarrow x 0 x 0 1 x 0 2 x 0 n nbsp zadana funkciya bagatoh zminnih f x X Y displaystyle f overrightarrow x X rightarrow Y nbsp Nehaj isnuye takij vektor A A 1 A 2 A n displaystyle overrightarrow A A 1 A 2 A n nbsp sho f x f x 0 A x x 0 o x x 0 displaystyle f overrightarrow x f overrightarrow x 0 overrightarrow A overrightarrow x overrightarrow x 0 o overrightarrow x overrightarrow x 0 nbsp pri x x 0 displaystyle overrightarrow x rightarrow overrightarrow x 0 nbsp de dobutok vektoriv ye skalyarnim dobutkom Poznachimo x x 0 d x d x 1 d x 2 d x n displaystyle overrightarrow x overrightarrow x 0 overrightarrow dx dx 1 dx 2 dx n nbsp Todi funkciya d f A d x displaystyle df overrightarrow A overrightarrow dx nbsp nazivatimetsya diferencialom funkciyi f x displaystyle f overrightarrow x nbsp v tochci x 0 displaystyle overrightarrow x 0 nbsp Priklad 2 Teper nehaj D f f x 1 D x 1 x 2 D x 2 x n D x n f x 1 x 2 x n displaystyle Delta f f x 1 Delta x 1 x 2 Delta x 2 x n Delta x n f x 1 x 2 x n nbsp pririst funkciyi f x 1 x 2 x n displaystyle f x 1 x 2 x n nbsp Neperervnist chastinnih pohidnih f x i displaystyle frac partial f partial x i nbsp ye umovoyu dostatnoyu dlya isnuvannya diferencialu U comu vipadkuD f i 1 n f x i D x i R 1 displaystyle Delta f sum i 1 n frac partial f partial x i Delta x i R 1 nbsp de R displaystyle R nbsp neskinchenno male u porivnyanni iz D x 1 2 D x 2 2 D x n 2 displaystyle sqrt Delta x 1 2 Delta x 2 2 Delta x n 2 nbsp Viraz d f i 1 n f x i D x i displaystyle df sum i 1 n frac partial f partial x i Delta x i nbsp ye diferencialom funkciyi bagatoh zminnih Vidobrazhennya mizh evklidovimi prostorami Redaguvati Diferencial vidobrazhennya golovna linijna vidnosno prirostu argumentu chastina vidobrazhenya yaka zadayetsya deyakoyu matriceyu Takozh ponyattya diferenciala mozhna vvesti dlya vidobrazhennya mizh evklidovimi prostorami ƒ Rn Rm Nehaj x Dx Rn dva vektori v prostori Rn Zmina znachennya funkciyi ƒ pri zmini argumentu na Dx rivna D f f x D x f x displaystyle Delta f f mathbf x Delta mathbf x f mathbf x nbsp Yaksho isnuye m n matricya A dlya yakoyi D f A D x D x e displaystyle Delta f A Delta mathbf x Delta mathbf x boldsymbol varepsilon nbsp de vektor e 0 pri Dx 0 todi ƒ nazivayetsya diferencijovnoyu v tochci x Matricya A nazivayetsya matriceyu Yakobi a linijne peretvorennya sho stavit u vidpovidnosti vektoru Dx Rn vektor ADx Rm nazivayetsya diferencialom dƒ x vidobrazhennya ƒ v tochci x Vidobrazhennya mizh mnogovidami Redaguvati Diferencial v tochci x M displaystyle x in M nbsp gladkogo vidobrazhennya iz gladkogo mnogovidu v mnogovid F M N displaystyle F colon M to N nbsp viznachayetsya yak linijne vidobrazhennya mizh dotichnimi prostorami v tochkah x M displaystyle x in M nbsp i F x N displaystyle F x in N nbsp tobto d F T x M T F x N displaystyle dF colon T x M to T F x N nbsp take sho dlya dovilnoyi gladkoyi v tochci F x funkciyi g N R displaystyle g colon N to mathbb R nbsp vikonuyetsya rivnist d F X g X g F X T x M displaystyle dF X g X g circ F quad forall X in T x M nbsp Dzherela RedaguvatiZavalo S T 1972 Elementi analizu Algebra mnogochleniv Kiyiv Radyanska shkola s 462 ukr Diferencial funkciyi Visha matematika v prikladah i zadachah Klepko V Yu Golec V L 2 ge vidannya K Centr uchbovoyi literaturi 2009 S 266 594 s Grigorij Mihajlovich Fihtengolc Kurs diferencialnogo ta integralnogo chislennya 2023 1100 s ukr Primitki Redaguvati Darling R W R 1994 Differential forms and connections Cambridge UK Cambridge University Press ISBN 0 521 46800 0 Eisenbud David Harris Joe 1998 The Geometry of Schemes Springer Verlag ISBN 0 387 98637 5 Boyer Carl B 1991 Archimedes of Syracuse A History of Mathematics vid 2nd John Wiley amp Sons Inc ISBN 0471543977 George G Joseph 2000 The Crest of the Peacock pp 298 300 Princeton University Press ISBN 0 691 00659 8 J L Berggren 1990 Innovation and Tradition in Sharaf al Din al Tusi s Muadalat Journal of the American Oriental Society 110 2 304 9 Dzhon Dzh O Konnor ta Edmund F Robertson Sharaf al Din al Muzaffar al Tusi v arhivi MacTutor angl nbsp Ce nezavershena stattya z matematiki Vi mozhete dopomogti proyektu vipravivshi abo dopisavshi yiyi Otrimano z https uk wikipedia org w index php title Diferencial matematika amp oldid 40287371