Quy ước trong toán học_ _ Math2IT.pdf

1/15/2015 Quyctrongtonhc?|Math2IT

http://math2it.blogspot.fr/2014/08/quyuoctrongtoanhoc.html 1/10

Math2ITDinh Anh Thi | 15.8.14 | Hiu ton hc | 2Like

Quy c trong ton hc?

Mt bi vit rt hay v vic hiu ng quy c trong ton hc. Quy c l g? C th chng minhc khng? M chng minh c sao li gi l quy c? Cng tm hiu vi tc gi blog Ton hcti p nh.

Trn mt din n n, mt thy gio dy Vt l bo vi mi ngi rng thy y c th chngminh c . Cch chng minh nh sau:

Nh vy c ngha l vic l hon ton chng minh c m khng cn phi quy cnh trong sch gio khoa lp 7. Rt nhiu ngi ng h, h bo rng chng minh n gin md hiu qu. M l chng minh c th cn phi quy c lm g?. Mt vi ngi phn i: l quy c th chng minh lm g? :) Vy l sao, c phi quy c hay khng? M tht ra myci quy c trong ton hc c ngha g, c th quy c khc i c hay khng?

Math2IT: Xin ni trc vi bn c y l nhng kin c nhn v lun bn vton hc ca tc gi bi vit, n khng mang tnh cht l chn l hay mt chngminh ton hc thun ty. Lp lun tuy da trn nhng logic ton hc nhng chmang tnh tham kho dnh cho mi ngi.

TRANG CH LATEX TON LINUX OS X CNTT TRI THC

KHC MATH2IT

tm



u tin cc bn phi hiu l mi chng minh u phi xut pht t nh ngha v cc tin c tha nhn. y ta xem xt ci nh ngha trong sgk nh:

(c tha s a).

nh ngha nh vy l hp l v tch ca n tha s a s l mt s no . nh ngha ny khngth p dng cho trng hp c v tch ca tha s a no c th c ngha l g? Ci trnghp ny r rng l khng c ngha g trong thc t. Tuy nhin do nhu cu pht trin ni ti caton hc ngi ta vn cn xt n . V y l lc cn phi quy c .

Vn l: cng ging nh bao quy c khc trong cuc sng, chng hn thay v ni mt triung ta c th quy c gi l mt chai, hay thay v gi th ny ta c th quy c gi th khc.iu quan trng l ch c quy c c nhn c s ng thun chung ca mi ngi haykhng m thi. l c im quy c trong ngn ng. Vy trn ta c th quy c c khng?

Cu tr li l Khng! Mi quy c trong ton hc u phi ph hp. Chc cc bn u bit tnhcht ny ca ly tha: . Nu m ln hn n, vic rt gn nhng tha s a ging nhau t v mu ta s cn li tch ca tha s , vy nn s bng vi .

Vic quy c s lm cho tnh cht trn vn cn ng trong trng hp . Timun nhn mnh li rng: mi quy c u phi ph hp v ha vo ci chung. Th nn vicchng minh quy c bng cch p dng tnh cht trn ging nh vic tha nhn n ng chng minh n ng vy! C l Thy y ch nn dng nhng phn tch ca mnh ch ra chohc sinh thy s hp l ca vic quy c m thi.

Nu cc bn cn hng th ti xin k tip mt cu chuyn na. C mt hc sinh k rng khi hcv tp hp con, c gio s dnh mt im 10 cho ai chng minh c rng: Tp rng l con cami tp hp. iu th v l trong cc ti liu v tp hp ngi ta u bo rng y ch l quyc! Rt kinh nghim t 1, chc cc bn s ngh rng: i do! l quy c ri cn chngminh ci g na?. Nhng khng hiu sao ln ny ti li mun ng h c gio y: ti ngh khngnh trn l c th chng minh c.

Ta nhc li mt cht v khi nim tp hp con: khi v ch khi

Vy nn chng minh tp rng l con ca mi tp A no ta cn chng minh:

(1)

Mi chuyn th v nm y: tnh ng sai ca mnh ko theo. Mnh ch sai khi ng m li sai thi. iu ny cng c ngha l khi P sai, bn mun suy ra ci g cng c!

Rt ging vi my tnh hung chm gi ca cc bn trai: Em ! Nu anh c nhiu tin th anh sxy cho em 2 ci h bi, mt ci cho em ra mt mt ci cho em ra chn! S thc l bn chngxy cho c y ci g c. D bn ang ngho kit, nhng ch cn ni nu anh c nhiu tin th

*

*

)

*

)*

) *

)*

) *

4 4 4

4 4 X 4

Ln u trang



8Comments Math2IT Login

SortbyBest Share

Jointhediscussion

noname 5monthsagoTrongtonhcngitakhngaiiquyciucthchngminhc.Vycuhitisaonhtrnthy"chngminh"lhpl,saocnhnkhngdngmiquyc?Phichnghusinhkhy?trliccvnnytixinmnmviyutsau:Luy,utinngitanhngha$a^n=a.a....a$,\foralln\inN=\{1,2,3,...\}$.Sau,dthyctnhcht$a^{m+n}=a^ma^n$,$\frac{a^m}{a^n}=a^{mn},\forallm>n,m,n\inN$.Gingitathyhnhnhctnhchtgchosmm,nghal$a^{n}=\frac{1}{a^n}$,iunycngtngtnh$a^{0n}=\frac{1}{a^n}$.Hay$a^0=1$.Nncuhitralngitasthmmt"tin"lhinnhin$a^{n}=\frac{1}{a^n}$c$a^0=1$hayngcli?Vthitnghkhngpgbngichnthanhnmtthnginnhtmmingithyhplchngminhiuphctphn.cnghpvilogiccaphttrin,khngaiixyciluitottchngminhmtmichicthtrma?Domicvic

Favorite

bn mun suy ra ci g m chng c. Th y, ci quy c ca ton hc n nm y: Tonhc quy c rng trong trng hp l Sai, mnh lun lun ng.

Tr li mnh (1) trn, ta thy rng: R rng mnh l sai vi mi phn t ( vrng c phn t no u). Nn mnh ko theo (1) l lun ng ri. iu c ngha l tprng ng l con ca mi tp hp m khng cn phi quy c. Ci quy c tht s y c ll ch quy c v tnh ng sai ca mnh ko theo m thi

2peoplelikethis.Bethefirstofyourfriends.Like

Dinh Anh Thi : Tc gi blog, xut thn l sinh vin s phm ton, hin ang l nghincu sinh v Ton ng dng ti Php. Chnh v nim am m Ton hc, tin hc ng dngv qua trng lp s phm nn Thi rt quan tm n vic ng dng Ton hc, Tin hcvo trong cuc sng thc t cng nh vic truyn t kin thc Ton cho hc sinh theomt phung php hin i v tch cc nht, gy hng th v hiu su cho ngi hc,ngi c ni chung. Mi chi tit xin lin h [email protected]. Blog c nhnAnh Thi blog.

4 X 4

15.8.14 Hiu ton hc

Vit bi cng blog bng cch lin h [email protected].



Reply

khngaiixyciluitottchngminhmtmichicthtrma?Domicviclachn$a^0=1$sauxydngvmrngcutrciscaphptnhlythasangchosm.Tmli,ccbiuthcmccbngilchngminhcho$a^0=1$trnchlingcliviconngcaphttrincaphptnhlytha.Trongkhingitathanhniunhb$a^0=1$,maicngcththynhpl,xydngphplythachosm.Chcccbnhctt.

1

Reply

inhAnhThi 5monthsagoMod >nonamebnning,cicchchngminhgingnhkiulycub)chngminhcua)trong1cuhivy.Tuynhinnhtcgibivitcp,quyctuyddngnhngphiphhpvilogictonhc,cthlcucngcngiquyca^0=2hongchng,nhngquaqutrnhsuylunlogicvthcttonhc,cibloitr.Vilia^0=1kophiaicngcththylnngu,bnthhihsbygivnhngngikochuyntonxemhbittisaohem,tinchmangtml"chpnhn"lchnhthi:)

Reply

noname 5monthsago>inhAnhThiNhni,bnthna^0=1lchpnhn.tmrngphptnhlythavncnngchosmm.Dohcsinhchpnhna^0=1lhinnhinm?

Reply

inhAnhThi 5monthsagoMod >nonamehinnhinvingithythi,cnhcsinhthchngchpnhntheokiuvt,mnhnilth.nhiukhimnhdychnga^0=2chngcngkonig,trnhngacbitrc,nhngathngminh.

PS.saukhickcommentcabn,mnhhiuthmcabnri,chcbncngchahiumnh,mnhkonila^0cthchngminhc,mnchmangtnhhpltonhcmthi.ivinhngngitipxcton,c2kiuchpnhn,1lchpnhnkiuvt,2lchpnhndicchhiucalogictonhc.

noname 5monthsago>inhAnhThiKohpllm:Nhvi5tinclic,chngtachpnhnn,xydngnnhnhhcclic.Gibo2ngthngsongsongkoctnhauclogicko,haychpnhnvt?th...khmnic.Nunhdngnhngtnhchthnhhcbnbitsauny,nilnlogic,thelhikhngcngbng,binhngcisaunylcsinhratmcan,nhngtincchpnhntrc.rimicchuynmtanhchngkhckinquytkochuchpnhntinsongsong,ngtaningclinctnhau,nunilogicthtathyisaomlonydhmth,haingsongsongrinhaurrngkoctnhaumhnboctnhiulngkhc,cuicnglisinhrahnh

Share

Share

Share

Share



Reply

koctnhaumhnboctnhiulngkhc,cuicnglisinhrahnhhcPhiclicmnhtnhngdngcanliykhoahcconngirangoikhnggian?

Vyclchpnhnvthaykhngvtliukhmlunbn,tanhnvothyncvhpl(kocnghallogic)tachpnhnnhnngxydngnnnhngcngtrnhkhcbngccphpsuylunlogic.Doniashcsinhchpnhnvttherngnhnxtcphntiucc.:D

Reply

inhAnhThi 5monthsagoMod >nonameHnhnhchngtaangivotranhcicphnvlthphi.Trckhitrlitipxinhibnclgiovinkhngvy?Tichngigiovinmibitlhcsinhchpnhnvtlnhthno.Mnhnithkhichngtadychohctr,cgng(mnhchnicgng)llmsaochochnghiubnchtvntrong1chngmcno.Vaphnkinthctonngynaydychohctrkophivtlg?Chngbaogicngcanhcnhtrongu1cuhi"hcchi?hcthi?"Ci"tiucc"bnnikodnhchohsmdnhchosgiodchs,dnhchochngtachngtartkinhnghim.

BnvdvtinphiEuclidelngnhngnhmnhni,chngtacquyngis,cquyn"chpnhnvtiv"nhbnni,ok,nutcha^0=2mbncthra1ngnhmi(gidnh"philytha"hayg)mnctnhllunthctinthvnok.Cimnhnillogictrongnhnggcphthinvconngichpnhntingyhmnay.

Xinnhcli,bnthntonhckophilthconngitora(tchngta"chpnhn"tchngtachonlphilcnocngclsai)mngnglinvinhucuvthctin.:D

Reply

noname 5monthsago>inhAnhThiPhichngbnanglycingcphasauangcnicitrcmtchngtamic?Xinhillythasm,lcictrclytha0,haythanhnmtcchhpllytha0mrngralythasm?,Nulmrcvn,tashiuciumnhangniylg.Mnhkonibthcsinhchpnhnmith,nhnglgiovincngnnhiutrnhtcakinthchcsinhchc.Nghalchabitnhngcisaulghtro,conngitamimmmi,nhngha,riphttrinnramtcchtnhin.Donuko"vt"chpnhna^0=1thccmycisaunychochngtahcko?Vybnchorngttincng"vt"ccthngyhmnay?

inhAnhThi 5monthsagoMod >noname

Share

Share

Share



Bi ng C hn

CchtofilevnbnbngLaTeX21comments5monthsago

haduyanhCmnbnnh.Mnhsacri

Ngnkhngchocopytextbivittrongblogger5comments6monthsago

holalatigeranhichoemhicinotevngvngtrongbivitmnhdngwidgetghayththutglmcvyanh,em

ThmhthngcommentDisQusvoblogger13comments6monthsago

inhAnhThia,mnhvnthynhcabnm?Khkhncabnlg,bnnirhnckhng?

SonthotonhctrongLaTeX(k1)4comments5monthsago

thuthaoNguyenlnThi^^

ALSOONMATH2IT

Reply

Rrngmnhngvibnngitacnbitcilythamlgnnngitaminhnghalytha0trc.

Vhshcdatrnnhnglthuytcchngminhlngnntinantmthahm"vt".Chkutonhcbnthnnvtmracimithcoichngkon.Vtphivttheokiunona,vttheokiuEuclideldatrnciclcatnhin.Chkophivttheokiu"i,bitonnykhqu,tavticigithitnyirichngminhtip",saingaycigcthlmsaongktquc?

Ttincngvtsainhiulmchkophitu,maymnthaysaunyngitakpphthin.

Cngnhmnh(dnton)anghcgiitchs,cnglptrnhmphng1hintngcatnhin.Titinhccnglptrnhnhvy.Tinra1biu,mnhcngrabiu.Cikhccbnca2bnchnhltinkoclluntonhcchngminhccphngtrnhvmhnhcatinlng.Rtnhiubibokhoahccng"gis"choranhiuktqunhngsaunyhcngphthinracigischathtsng.Thmchhctnhgiskothctgiinhngbitonngintrcdbitrngnsai.vttheokiucatitinthnguyhimlm,sai1lii1dm.

WHAT'STHIS?

Subscribe AddDisqustoyoursited Privacy

Share

Bi ng Mi hn



Tuyn tp cc eBooks hiu thmv th gii ton hc k th (cp

nht ngy 10/12/2014)

Tnh hp l ca nghim hphung trnh v khi nim

'condition number' ca mt ma trn (k1)

vui: Anh chng chy xe (pn)

Cc website hay dnh cho vichiu ngha thc tin ca ton

hc (update 12/9/2014)

Hiu v khi nim 'gii hn' trongton hc (k 2)

Bi lin quan

Gii thiu

Math2IT l chuyn trang v Ton hc+ Gio dc v Cng ngh. Mongmun chia s tri thc v kht khao imi nn gio dc nc nh. cthm.

Theo di chng ti

+38 xut url ny trn Google

Nhiu nht 7 ngy qua

Nhng cch v hnh chnh xc bng

Math2ITTon&Tin1,461Like



thc k v compa

Nhng vic cn lm sau khi ciUbuntu 14.04 v mt s phin

bn khc

Nhng phn mm nn ci choUbuntu, Elementary OS, Linux

Son tho ton hc trong LaTeX(k 1)

WolframAlpha : gii ton theotng bc

Tng hp nhng vic cn lmsau khi ci Windows c mt

chic my tnh y mnh m

Ti liu tham kho dnh cho itng t hc LaTeX (cp nht

ngy 6/11/14)

Bi ngu nhin

Nhng bi vit ang trong giaion hon tt

[TeXTips] Thm t kha gi lcg trong TeXMaker

Nhng li LaTeX thng gpnht

vui: Anh chng chy xe (pn)

Chuyn file hnh trong Matlabsang code hnh v trong LaTeX

Nhiu nht 30 ngy qua

Nhng cch v hnh chnh xcbng thc k v compa

Nhng vic cn lm sau khi ciUbuntu 14.04 v mt s phin



bn khc

Nhng phn mm nn ci choUbuntu, Elementary OS, Linux

Ti liu tham kho dnh cho itng t hc LaTeX (cp nht

ngy 6/11/14)

Son tho ton hc trong LaTeX(k 1)

WolframAlpha : gii ton theotng bc

Google+

Math2IT

+ 38

Theo di

Lt xem

111191

Nhn xt mi

Ti liu min ph

bn c th cho mnh xin link face cabn.. mnh c th trao i trc tip vibn.. bn gip...

To phn trang c nh s cho blogger 2 hours ago

inh Anh Thi

a, mnh thy n khi n lch th mi pm bn, khi y th cc bi n "kht" lic vi nhau...

To phn trang c nh s cho blogger 3 hours ago

Ti liu min ph

Bn inh Anh Thi cho mnh hi thm ci



ANDROID BLOGGER-BLOGSPOT CHUYN TON HC

EBOOK GAME GIO DC HIU TON HC

HI P HI P LATEX HI P TIN

HI P TON KHC KHM PH

KIN THC CNG NGH KIN THC THPT LATEX

LINKS LINUX LI LATEX MATH2IT OSX

PHN MM TEX CHUYN NGNH TEXTIPS

TH THUT IT TON TON CAO CP TON S CP

TI SAO T HC LATEX THI VUI

ny na nh !! hjhj trn trang ch blogbi ng n c b...

To phn trang c nh s cho blogger 12 hours

ago

inh Anh Thi

Hix, mnh cng nh mua n bn, mnhkhng r bn i, thng th bn nn hicng ty bn tn min...

To phn trang c nh s cho blogger 1 day ago

Theo di qua email

Emailcabn... SUBMIT

Chuyn mc

2012 Math2IT | Thit k bi Template Trackers | Chnh sa bi inh Anh Thi

Quy ước trong toán học_ _ Math2IT.pdf

Documents

Transcript of Quy ước trong toán học_ _ Math2IT.pdf