chislovie ryadi

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chislovie ryadi osnovnie ponyatiya chislovix ryadov. neobxodimie usloviya sxodimosti ryadov. teoremi sravneniya polojitelnix ryadov. dostatochnie usloviya sxodimosti ryadov: znak dalambera, radikalniy i tselochislenniy znaki koshi. znakoperemennie ryadi. teorema leybnitsa. absolyutniy i uslovno sxodyashiysya ryad. linii teylora i maklorena plan: 1. osnovnie ponyatiya i neobxodimie usloviya sxodimosti 2. dostatochnie priznaki sxodimosti dlya polojitelnix ryadov 3. znakoperemennie ryadi i stepennie razlojeniya 1. osnovnie ponyatiya i neobxodimie usloviya sxodimosti chislovie ryadi yavlyayutsya odnim iz fundamentalnix ponyatiy matematicheskogo analiza. ryad predstavlyaet soboy beskonechnuyu summu chisel, kotoraya zapisivaetsya kak: n=1∑∞​an​=a1​+a2​+a3​+⋯+an​+… gde an​ — eto obshiy chlen ryada (ili n-y chlen ryada). osnovnie ponyatiya obshiy chlen ryada (an​) formula obshego chlena ryada yavlyaetsya opredelyayushey xarakteristikoy. znanie an​ pozvolyaet vichislit lyuboy chlen ryada i, chto samoe glavnoe, issledovat ego sxodimost. chastichnaya summa ryada (sn​) chastichnaya summa sn​ — eto summa pervix n chlenov ryada: sn​=a1​+a2​+⋯+an​=n=1∑n​an​ posledovatelnost chastichnix summ {sn​} yavlyaetsya klyuchevim elementom dlya opredeleniya sxodimosti ryada. sxodimost …
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utsya putem sopostavleniya issleduemogo ryada s drugim ryadom, sxodimost kotorogo uje izvestna. 1. priznak sravneniya v obichnoy forme (neravenstvo) teorema: pust dani dva polojitelnix ryada ∑an​ i ∑bn​. 1. esli an​≤bn​ nachinaya s nekotorogo nomera n0​, i ryad ∑bn​ sxoditsya, to i ryad ∑an​ sxoditsya. 2. esli an​≥bn​ nachinaya s nekotorogo nomera n0​, i ryad ∑bn​ rasxoditsya, to i ryad ∑an​ rasxoditsya. v kachestve etalonnix (sravnivaemix) ryadov chasto ispolzuyut: · ryad dirixle (obobshenniy garmonicheskiy ryad): ∑n=1∞​np1​. sxoditsya, esli p>1; rasxoditsya, esli p≤1. · geometricheskiy ryad: ∑n=0∞​qn. sxoditsya, esli ∣q∣ 1 (ili l=∞), ryad rasxoditsya. 3. esli l=1, priznak ne daet otveta (trebuetsya ispolzovat drugoy priznak). priznak d’alambera osobenno effektiven dlya ryadov, soderjashix faktoriali (n!) i stepennie funktsii (an), tak kak pri vzyatii otnosheniya proisxodit silnoe sokrashenie. 2. radikalniy priznak koshi (cauchy's root test) etot priznak ispolzuet predel kornya n-y stepeni iz obshego chlena. teorema: pust dlya polojitelnogo ryada ∑an​ sushestvuet …
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∑np1​. vivod: pri issledovanii polojitelnix ryadov rekomenduetsya sleduyushiy poryadok deystviy: 1) proverka neobxodimogo usloviya. 2) ispolzovanie priznakov d’alambera ili koshi (dlya ryadov s faktorialami/stepenyami). 3) ispolzovanie priznakov sravneniya (dlya sravneniya s ryadami dirixle). 4) ispolzovanie integralnogo priznaka (dlya funktsiy, legko integriruemix). 3. znakoperemennie ryadi i stepennie razlojeniya znakoperemennie ryadi – eto ryadi, chleni kotorix mogut prinimat kak polojitelnie, tak i otritsatelnie znacheniya. oni delyatsya na znakochereduyushiesya i ryadi s proizvolnim cheredovaniem znakov. znakochereduyushiesya ryadi znakochereduyushiysya ryad – eto chastniy sluchay znakoperemennogo ryada, gde znaki sosednix chlenov chereduyutsya strogo po ocheredi: n=1∑∞​(−1)n−1an​=a1​−a2​+a3​−a4​+… gde an​>0. teorema leybnitsa (leibniz's test) eta teorema daet prostoe dostatochnoe uslovie sxodimosti dlya znakochereduyushixsya ryadov. teorema (priznak leybnitsa): znakochereduyushiysya ryad ∑n=1∞​(−1)n−1an​ sxoditsya, esli vipolnyayutsya dva usloviya: 1. chleni ryada monotonno ubivayut po absolyutnoy velichine: a1​≥a2​≥a3​≥⋯≥an​≥… 2. obshiy chlen ryada stremitsya k nulyu: limn→∞​an​=0. otsenka ostatka ryada leybnitsa: esli ryad sxoditsya po priznaku leybnitsa, to ego ostatok rn​=s−sn​ (raznost …
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ki absolyutnoy sxodimosti ispolzuyutsya priznaki d’alambera i koshi, primenennie k ryadu ∑∣an​∣. 2. uslovnaya sxodimost ryad ∑an​ nazivaetsya uslovno sxodyashimsya, esli sam ryad sxoditsya, a ryad, sostavlenniy iz absolyutnix velichin, rasxoditsya (t.e. ∑an​ sxoditsya, a ∑∣an​∣ rasxoditsya). uslovno sxodyashiesya ryadi obladayut paradoksalnim svoystvom: ix summa mojet izmenitsya (i daje stat lyuboy napered zadannoy) pri izmenenii poryadka slagaemix (teorema rimana). ryadi teylora i maklorena ryadi teylora i maklorena yavlyayutsya klyuchevim zvenom, soedinyayushim chislovie ryadi s funktsionalnimi (stepennimi) ryadami. stepennoy ryad stepennoy ryad — eto funktsionalniy ryad spetsialnogo vida: n=0∑∞​cn​(x−x0​)n=c0​+c1​(x−x0​)+c2​(x−x0​)2+… gde x0​ — tsentr ryada, a cn​ — koeffitsienti. oblast sxodimosti stepennogo ryada vsegda yavlyaetsya intervalom sxodimosti, simmetrichnim otnositelno x0​. ryad teylora esli funktsiya f(x) beskonechno differentsiruema v okrestnosti tochki x0​, to ee ryad teylora opredelyaetsya kak: f(x)≈n=0∑∞​n!f(n)(x0​)​(x−x0​)n koeffitsienti ryada cn​=n!f(n)(x0​)​ odnoznachno opredelyayutsya proizvodnimi funktsii v tsentre razlojeniya. ryad maklorena ryad maklorena — eto chastniy sluchay ryada teylora pri x0​=0: f(x)≈n=0∑∞​n!f(n)(0)​xn ryadi …
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skonechnix ryadov, otkrivaya moshnie metodi approksimatsii.

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chislovie ryadi osnovnie ponyatiya chislovix ryadov. neobxodimie usloviya sxodimosti ryadov. teoremi sravneniya polojitelnix ryadov. dostatochnie usloviya sxodimosti ryadov: znak dalambera, radikalniy i tselochislenniy znaki koshi. znakoperemennie ryadi. teorema leybnitsa. absolyutniy i uslovno sxodyashiysya ryad. linii teylora i maklorena plan: 1. osnovnie ponyatiya i neobxodimie usloviya sxodimosti 2. dostatochnie priznaki sxodimosti dlya polojitelnix ryadov 3. znakoperemennie ryadi i stepennie razlojeniya 1. osnovnie ponyatiya i neobxodimie usloviya sxodimosti chislovie ryadi yavlyayutsya odnim iz fundamentalnix ponyatiy matematicheskogo analiza. ryad predstavlyaet soboy beskonechnuyu summu chisel, kotoraya zapisivaetsya kak: n=1∑∞​an​=a1​+a2​+a3​+⋯+an​+… gde an​ — eto obshiy chlen ryad...

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