一元二次方程的解法課件市公開課一等獎省課獲獎課件

配措施2一元二次方程解法第1頁開心練一練：

(1)(2)2、下列方程能用直接開平辦法來解嗎?創(chuàng)設情境溫故探新1、用直接開平辦法解下列方程:靜心想一想：(1)(2)把兩題轉(zhuǎn)化成(x+b)2=a(a≥0)形式，再利用開平方X2+6X+9=2第2頁(1)(2)(3)=(+)2=(

)2=(

)2左邊:所填常數(shù)等于一次項系數(shù)二分之一平方.填上合適數(shù)或式,使下列各等式成立.大膽試一試：共同點：()2=(

)2(4)自主探究觀測(1)(2)看所填常數(shù)與一次項系數(shù)之間有什么關系?第3頁

問題：要使一塊矩形場地長比寬多6m，并且面積為16m2，場地長和寬應各是多少？（1）解：設場地寬為X米，則長為（x+6）米，根據(jù)題意得:

整頓得：X2+6X－16=0合作交流探究新知X（X+6）=16

第4頁

移項兩邊加上32,使左邊配成左邊寫成完全平方形式降次第5頁例1:用配辦法解方程解:配方得：開平方得：移項得：∴原方程解為：心動不如行動第6頁例2:你能用配辦法解方程嗎？解:配方得：開平方得：范例研討利用新知移項得：∴原方程解為：化二次項系數(shù)為1得：二次項系數(shù)不為1又怎么辦?想一想用配辦法解一元二次方程一般有哪些步驟?例2:你能用配辦法解方程嗎？第7頁反饋練習鞏固新知1、用配辦法解下列方程:(1)x2+8x-15=0(2)x2-5x-6=0(3)2x2-5x-6=0(4)x2+px+q=0(p2-4q＞

0)

第8頁課堂小結布置作業(yè)小結：（2）移項（3）配方（4）開平方（5）寫出方程解2、用配辦法解一元二次方程ax2+bx+c=0(a≠0)步驟：1、配辦法：

通過配方,將方程左邊化成一種含未知數(shù)完全平方式,右邊是一種非負常數(shù),利用直接開平方求出方程解辦法。(1)化二次項系數(shù)為1第9頁Chapter5Historicalstories第10頁pyramid金字塔Stonehenge巨石陣第11頁wheel車輪goldensunlight.金色陽光第12頁Tian’anmenSquare天安門廣場army

軍隊第13頁JayChou周杰倫JayChouishandsome.Heismyfavouriteactor.第14頁arrow箭bow弓第15頁

TheTrojanWar第16頁HistoricalstoriesNotesabout

theTrojanWartoldinHomer’sIliad

andOdyssey．荷馬伊利亞特奧德賽

theprinceofTroyfellinlovewithHelen,thequeenofSparta.斯巴達

HekidnappedherandtookhertoTroy.AlltheGreekwenttobringherback.綁架

thewarlastedfortenyears.第17頁

Thenightofthehorse第18頁SkimmingLookat

thetitle,thepicture

and

thelastparagraph,andthenanswerthetwoquestions.Itwasahugewoodenhorse.Whatkindofhorseitis?2.HowdidtheGreekswinthewar?Theywonthewarwithatrick.第19頁Readthroughthewholepassageandmatchthemainideaforeachpart.P1-2P3-6P7P8-9TheTrojanscelebratetheirvictoryandthengotosleep.TheGreeksoldiersinsidethehorseopenthecitygatesandletintheGreekarmy.TheGreekarmycaptureTroy.ATrojansoldierannouncesthattheGreekarmyhasleftandhiscaptainConfirmsit.Thesoldierfoundahuge,woodenhorseoutsidetheircity,andthecaptainordersittobemovedintothecity.第20頁1.Howwasthesoldierprobablyfeelingwhenhecamedownthestairs,surprisedorpeaceful?2.Whatdidthecaptainthinkwhenhesawtheemptyplain?3.Whatdidthecaptainthinkaboutthehorse?4.WhatdidthecitizensofTroydothatnight?5.WheredidthesixGreeksoldiershide?6.Didthehorsehavesomethingtodowiththetrick?How?Readthepassageandthenanswerthefollowingquestions第21頁1.Howwasthesoldierprobablyfeelingwhenhecamedownthestairs,surprisedorpeaceful?2.Whatdidthecaptainthinkwhenhesawtheemptyplain?3.Whatdidthecaptainthinkaboutthehorse?ReadthepassageandthenanswerthefollowingquestionsHeprobablywasfeelingsurprised.Thecaptainthoughtthattheyhadwonthewar.HethoughtitwastoobigfortheGreekstotake.第22頁4.WhatdidthecitizensofTroydothatnight?

5.WheredidthesixGreeksoldiershide?6.Didthehorsehavesomethingtodowiththetrick?How?Theycelebratedtheirsuccess.Theyhidinthehorse.Yes.(answersvary.)第23頁PartBLookandthink

ThesepicturesshowsomeoftheeventsinthestoryonPage58.Arrangetheminthecorrectorder.

Answers:cdbafe第24頁

Summary

ThewarbetweentheTroyandtheGreekslastedtenyears.Atlast,theGreekswonthewarwithat___.TheypretendedtoleavethecityofTroy,buttheyleftahugew______horsebehind.TheTroythoughttheyhavew__thewarsotheyc________,makingj____abouttheGreeks.Theyweresohappyabouttheirwinthatallofthemwenttosleep,i________thegateguard.TheGreeksoldiersi_____thewoodenhorseopenedthegateandlettheirarmyin.Inthisway,theyc_____theTroycity.rickoodenonelebratedokesncludingnsideaptured第25頁1.大木馬2.舉辦一次比賽3.沖下臺階4.一會兒后5.朝下看6.再多等一小時7.進入城里8.拿走，帶走9.除…之外10.拖…進城11.開…玩笑12.成功做成某事13.用計策ahugewoodenhorsehave\hold\runacompetitionrushdownthestairssecondslaterlookdownatwaitforanotherhour=waitforonemorehourenterthecity=getintocitytakeawayexceptforpull/drag…intothecitymakejokesabout=laughat=makefunofsucceedindoingsth.withatrick第26頁

Usefulexpressions1.Anewspaperranashortcompetitiononfamoustalesfromhistory.compete(v)比賽competitioncompetitor

competitive(n.)比賽(n.)比賽者(adj.)比賽第27頁2.Secondslater,thecaptainstoodonthehighwallofthecityofTroy,andlookeddownattheemptyplain.(1)secondslater=afterawhile一會兒后(幾秒鐘后)(2)thecityofTroy特洛伊城

thecityofShenzhen=Shenzhencity(3)lookout=becarefullookfor尋找

lookafter照顧

lookover=examinelookdownuponsb看不起某人

lookupto看得起，尊重第28頁3.Itwastoobigforthemto

takewiththem.=Itwassobigthat

theycouldn’ttakeitwiththem.

takebringcarry隨身攜帶第29頁4.Theyallwenttosleep,includingthegateguards.Thebandplayedmanysongs,includingsomeofmyfavorite.

十個人出席了會議，包括我爸爸。

Tenmembersarepresentatthemeeting,includingmyfather.5.Bymidnight,thesquarewasempty,exceptforthegianthorse.

exceptfor:notincluding除…之外（不包括）

Exceptforoneoldlady,thebuswasempty.

比較：

WegotoschooleverydayexceptSaturdayandSunday.Wehavewinterholidaybesidessummerholiday.第30頁6.ThesixGreeksoldiersinthewoodenhorsewaitedforanotherhour,tobesure.Weneedanothertenstudents

=Weneedtenmorestudents.第31頁

Paraphrase1.TheGreekstriedtocaptureourcity.2.Thesquarewasempty,exceptforthegianthorse.

3.Theysucceededincapturingitwithatrick.TheGreekstriedtotakeoverourcity.Therewasnobodybutthegianthorseinthesquare.Therewasonlyagianthorseinthesquare.Theymanagedtocaptureitwithatrick.Theycaptureditsuccessfullywithatrick.第32頁Listening1d--2h--3a--4e--5b--6g--7c--8f第33頁TroySpartaGodsandGoddessesKingofTroyKingMenelausKingoftheGodsZeusPrinceParisQueenHelenGoddessofloveAphroditeHowdidtheTrojanWarstart?1d--2h--3a--4e--5b--6g--7c--8f第34頁Grammarthepresentperfecttense第35頁Translatethefollowingsentences1.我已經(jīng)寫了幾個電腦游戲。2.我經(jīng)營這家公司兩年了。3.你把你書整頓好了嗎？4.我還沒有把衣服掛起來。5.他鋪床鋪了嗎？Ihavealreadywrittenseveralcomputergames.Ihaverunthebusinessfortwoyears.Haveyouorganizedyourbooks?Ihaven’thunguptheclothes.Hashemadethebed?第36頁目前完成時構造：have/has+動詞過去分詞第37頁一.動詞過去分詞形式1.規(guī)則動詞finish--finished--finishedlive--lived--livedcarry--carried--carriedstop—stopped--stoppedfailorganizeachieveempty--failed—failed--organized--organized--achieved–achieved--emptied–emptied第38頁2.不規(guī)則動詞go—went—goneseesaw—seenforgetspendsweephang—forgot—forgotten—spent—spentsweptswepthunghung第39頁

(1).for+表達一段時間短語

(2).since+表達過去時間點詞語

(3).since+表達過去時間時間狀語從句eg.Ihavebeenateacher______ayear.Hehasbeenatthisschool_______1992.Wehavelearned1,000Englishwords_______wecametothisschool.forsincesincealready,yet;never,ever;just,before

有此類副詞時,常強調(diào)動作完成.

eg.Haveyou_____beentoJapan?Ihave_____finishedmyhomework.Ihave________finishedmyhomework.

Ihaven’tfinishedmyhomework____.everjustalreadyyet二.目前完成時句中常見時間詞第40頁1.We’vealreadyfinishedthework.Ihaven’tswepttheflooryet.Haveyouemptiedtherubbishbinyet?already已經(jīng)－－用于肯定句

yet還－－用于疑問句和否認句第41頁2.Shehasneverheardofit,hasshe?HaveyoueverbeentoEngland?never從未－－沒做過

ever曾經(jīng)－－做過第42頁3.I’vejustwrittenseveralcomputergames.Ihavewatchedthisfilmbefore.just剛才

before此前第43頁

用

since,for或者ago填空1.JillhasbeeninIreland_____Monday.since2.JillhasbeeninIreland___threedays.for3.MyaunthaslivedinAustralia____15years.for4.Margaretisinheroffice.Shehasbeenthere____7o’clock.since5.Mikehasbeeninhospital_____October.since6.Theygotmarriedsixmonths_____.ago7.IfirstmetSuetwoyears____.ago第44頁三.辨別短暫性動詞與連續(xù)性動詞.

表達短暫性(瞬間性)動詞在目前完成時句中不能和一段時間連用.即for,since短語或howlong問句第45頁Icameheretwoyearsago.Ihavebeenherefortwoyears.Ihavebeenheresincetwoyearsago.2.Ijoined

thearmy5yearsago.Ihavebeenasoldierfor5years.第46頁come/arrivegooutleavebeginbuyborrowjoindiecatchacoldbeat/in…beoutbeaway(from)beonhavekeepbeamemberofbedeadhaveacold第47頁瞬間動詞和延續(xù)性動詞轉(zhuǎn)換練習：1.Iboughtthebooktwodaysago.Ihavehadthebookfortwodays.2.Heborrowedthebookthreemonthsago.Hehaskeptthebooksince3monthsago.3.IgottoknowJane2yearsago.IhaveknownJanefor2years.4.IjoinedtheLeaguethreeyearsago.IhavebeenaLeaguememberfor3years.第48頁5.Kenjoinedthearmytwoyearsago.Kenhas_____________fortwoyears.Kenhas_______thearmyfortwoyears.beenasoldierbeenin6.Helefthishometown10yearsago.Hehas_____________hishometownsince10yearsago/for10years.beenawayfrom第49頁7.Thefilmbegan10minutesago.Thefilmhas________for10minutes.beenon8.Igotacoldtwodaysago.Ihave____acoldsincetwodaysago.had9.Thefilmfinished5minutesago.Thefilmhas________for5minutes.beenover10.Themancameheretenminutesago.Themanhas____herefor10minutes.been11.LindaandFrankmarriedin1989.They_________________since1989.havebeenmarried第50頁改錯:Howlonghaveyoubecomealeaguemember？

Formorethanoneyear.Haveyouarrivedheresincelastnight.Yes，you’reright.Thedoghasdiedforamonth.HehasgonetoShanghaitwice.Howlonghaveyoubeenatthisschool?S