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过椭圆C:=1(a>b>0)的左焦点F的直线过C的上端点B,且与椭圆相交于点A,若,则C的离心率为( )
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高三下学期数学《》真题及答案
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设椭圆+=1a>b>0的左焦点为F.离心率为过点F.且与x轴垂直的直线被椭圆截得的线段长为.1求椭圆
设椭圆中心在坐标原点焦点在x轴上一个顶点坐标为20离心率为.1求这个椭圆的方程2若这个椭圆左焦点为F
已知椭圆中心在原点焦点在x轴上离心率点F1F2分别为椭圆的左右焦点过右焦点F2且垂直于长轴的弦长为1
已知椭圆过焦点垂直于长轴的弦长为1且焦点与短轴两端点构成等边三角形.1求椭圆的方程2过点Q.-10的
焦点分别为F1F2的椭圆过点M21抛物线的准线过椭圆C的左焦点.Ⅰ求椭圆C的方程Ⅱ不过M的动直线l交
过椭圆+y2=1的左焦点F.作斜率为kk≠0的直线交椭圆于
,
两点,使得AB的中点M.在直线x+2y=0上,则k的值为( ) A.1B.2
﹣1
﹣2
设分别为椭圆的左右两个焦点若椭圆C.上的点A.1到F1F2两点的距离之和等于4.⑴写出椭圆C.的方程
设椭圆=1a>b>0的左焦点为F.短轴上端点为B.连接BF并延长交椭圆于点A.连接AO并延长交椭圆于
椭圆C.过点离心率为左右焦点分别为F.1F.2过F.1的直线交椭圆于A.B.两点.1求椭圆C.的方程
已知椭圆的左右焦点分别为F.1F.2过F.1的直线交椭圆于B.D.两点过F.2的直线交椭圆于A.C.
已知椭圆C.+=1a>b>0的左右焦点分别为F.1F.2离心率为过F.1的直线交椭圆于E.F.两点且
已知F1F2为椭圆=la>b>0的左右焦点B1B2椭圆短轴的端点四边形F1B1F2B2为正方形且面积
设F.1F.2分别为椭圆的左右两个焦点若椭圆C.上的点A.1到F.1F.2两点的距离之和等于4.1写
已知直线x-2y+2=0过椭圆+=1a>0b>0a>b的左焦点F1和一个顶点B.则该椭圆的离心率e=
设双曲线以椭圆+=1长轴的两个端点为焦点其准线过椭圆的焦点则双曲线的渐近线的斜率为__.
已知椭圆C.+=1a>b>0的左焦点F.1与抛物线y2=﹣4x的焦点重合过点F.1的直线l交椭圆于A
过点C01的椭圆 的离心率为 椭圆与x轴交于两点Aa0B-a0过点C的直线l与椭圆交于
以椭圆的右焦点F.2为圆心作一个圆使此圆过椭圆中心O.并交椭圆于点M.N.若过椭圆左焦点F.1的直线
相交
相离
相切
位置关系随离心率改变
过椭圆C+=1a>b>0的左焦点F的直线过C的上端点B且与椭圆相交于另一个点A若|BF|=3|AF
已知F.1F2是椭圆a>b>0的左右两个焦点A.是椭圆上一点△AF1F2的周长为10椭圆的离心率为1
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15分FormorethansixmillionAmericanchildrencominghomeafterschoolmeans1cometoanemptyhouse.SomedealwiththesituationbywatchingTV.Somemayhangoutoutside.2allofthemhavesomethingincommon.Theyspendpartofeachdayalone.They3calllatchkeychildren﹣theyarechildrenwholookafterthemselveswhiletheirparentswork.Andtheirbadsituationhasbecomeasubjectofconcern. Aheadmasterofanelementaryschoolsaidthattherewasaschoolruleagainstwearingjewelry.Alotofkidshadchainsaroundtheirneckswithkeys4attach.Hewasconstantlytellingthemtoputtheminsideshirts.Thereweresomanykeysallof5werehousekeys. Hebegantalkingtothechildrenwhohadthem.Thenhelearnedtheinfluencethatworkingcouplesandsingleparentswerehaving6theirchildren.Fearisthebiggestproblemfacedbychildrenathomealone.Manyhadnightmaresandwereworriedabouttheirown7safe. Themostcommonwaylatchkeychildrendealwiththisisbyhiding.Itmightbeinabathroomunderabed8inacloset.ThesecondisTV.They'llwatchitwiththevolumeturneduphigh.Mostparentsdon'trealize9iteffectontheirchildrenandmostparentsareslowtoadmitthefact10theyleavetheirchildrenalone.
已知三棱锥P﹣ABC的四个顶点都在半径为3的球面上AB⊥AC则该三棱锥体积的最大值是
25分阅读下面短文根据其内容写一篇60词左右的内容概要. FormostofussocialmedialikeTwitterandFacebookisapartofoureverydaylives﹣atworkhomeorboth.Butalotofpeoplearestillfiguringoutwhentouseitandhow.Thisisespeciallytrueinhighschoolwheremanyteachersareunsureofhowitfitsintheclassroom. DanKrutkaahighschoolteacherisanadvocateforusingsocialmediaintheclassroomandisanenthusiasticuserofTwitterhimself.Krutkasaysit'sagreatwaytocommunicatewithhisstudentsduringnonclasshours.YoucancontinuetolearntogetheroutsidetheclassroomsaysKrutka.SowhenstudentsarepostingonTwitter﹣saytheypostsomethinginaccuratelyortheymakeareallygoodpoint﹣Icangoaheadandrespondtothembeforeclass. Krutkasaystweetingwithhisstudentsisn'tjustaboutconvenienceit'salesson.Hesaysstudentsneedtolearnhowtousesocialmediaproperly.Peopleusesocialmediairresponsiblyandschoolshouldbeaplacewherewe'retalkingaboutthatandhowtouseitresponsiblyhesays.AsateacherIthinkpartofmyjobistohelpstudentsunderstandhowtomakebestuseofitasthoughtfullearners. ButKrutkaisamongthefeweducatorswhofeelthisway.ManyschoolsincludingthoseinWesternMassachusettsarestillstrugglingwithwhetherornotTwitterorFacebookshouldbeusedasteachingtools.Manyteachersbelievethatsocialmediaingeneralcaneasilydistractstudents.SeanKavanaghaninthgradeworldhistoryteachertriedusingTwitterinclassbutwasdistractedbyallofthenonclassrelatednoise. Besidesitseemsthatsomestudentsdon'tfeellikethiswayeither.RayLynnisinKavanagh'shistoryclass.I'dratherkeepmyschoolandmypersonalsocialmedialifealittlemoreseparateshesays.I'drathernothavemyteacheronmyTwitterorFacebook.
己知xy满足则x﹣2y的最大值为
回答下列与生态系统相关的问题. 1在森林生态系统中生产者的能量来自于生产者的能量可以直接流向答出2点即可. 2通常对于一个水生生态系统来说可根据水体中含氧量的变化计算出生态系统中浮游植物的总初级生产量生产者所制造的有机物总量.若要测定某一水生生态系统中浮游植物的总初级生产量可在该水生生态系统中的某一水深处取水样将水样分成三等份一份直接测定O2含量A另两份分别装入不透光甲和透光乙的两个玻璃瓶中密闭后放回取样处若干小时后测定甲瓶中的O2含量B和乙瓶中的O2含量C.据此回答下列问题. 在甲乙瓶中生产者呼吸作用相同且瓶中只有生产者的条件下本实验中C与A的差值表示这段时间内C与B的差值表示这段时间内A与B的差值表示这段时间内.
7.5分The13thofJune1325IleftTangiermybirthplacewiththeintentionofmakingthepilgrimagetoMecca去麦加朝圣…toleaveallmyfriendstoabandonmyhomeasbirdsabandontheirnests.SobeginsanoldmanuscriptinalibraryinParis﹣thetraveldiaryofIbnBattuta. AlmosttwocenturiesbeforeColumbusthisyoungMoroccansetoffforMeccareturninghomethreedecadeslaterasoneofhistory'sgreattravelers.DrivenbycuriosityhejourneyedtoremotecornersoftheIslamicworldtravelingthrough44moderncountriesthreetimesasfarasMarcoPolo.LittlecelebratedintheWesthisnameiswellknownamongArabs.InhishometownofTangierasquareahotelacafeaferryboatandevenahamburgerarenamedafterhim. IbnBattutastayedinMeccaasastudentforseveralyearsbuttheurgetotravelsoontookover.InoneadventurehetraveledtoIndiaseekingprofitableemploymentwiththesultan﹣theMuslimrulerofDelhi.Onthewayhedescribedhisgroupbeingattackedintheopencountryby80menonfootandtwohorsemen…IwashitbyanarrowandmyhorsebyanotherbutGodinhisgracepreservedme…InDelhithesultangavehimthepositionofjudgebasedonhispreviousstudyatMecca.ButthesultanhadanunpredictablecharacterandIbnBattutalookedforanopportunitytoleave.WhenthesultanofferedtofinanceatriptoChinaheagreed.IbnBattutasetoffinthreeshipsbutmisfortunestruckwhilehewasstillontheshore.Asuddenstormgroundedandbrokeuptwoshipsscattering散播treasureanddrowningmanypeopleandhorses.Ashewatchedthethirdshipwithallhisbelongingsandslaves﹣onecarryinghischild﹣wascarriedouttoseaandneverheardfromagain. AfteralifetimeofamazingadventuresIbnBattutawasfinallyorderedbytheSultanofMoroccotoreturnhometosharehiswisdomwiththeworld.Fortunatelyheagreedandwroteabookthathasbeentranslatedintonumerouslanguagesallowingpeopleeverywheretoreadabouthisunparalleledjourneys. 1WhatcanwelearnaboutIbnBattutafromthepassage? A.HehadgreatinterestintheIslamicworld. B.Hereturnedtohishomelandtowriteabook. C.HisjourneyswerelessimportantthanMarcoPolo's. D.Hisjourneyswereverycommonforpeopleofthattime. 2TheSultanofDelhigaveIbnBattutaapositionofjudgebecause. A.IbnBattutahadstudiedinMecca B.IbnBattutahadbeenajudgebefore C.IbnBattutahadbeenpopularwithArabs D.IbnBattutahadtraveledtomanycountries 3Whichisthebesttitleforthepassage? A.TheLearnedIbnBattuta B.AVisitortoMecca C.TheTravelsofIbnBattuta D.DesireforAdventures
物质W是一种含氮有机物会污染土壤.W在培养基中达到一定量时培养基表现为不透明.某研究小组欲从土壤中筛选出能降解W的细菌目标菌.回答下列问题. 1要从土壤中分离目标菌所用选择培养基中的氮源应该是. 2在从土壤中分离目标菌的过程中发现培养基上甲乙两种细菌都能生长并形成菌落如图所示.如果要得到目标菌应该选择菌落进一步纯化.选择的依据是. 3土壤中的某些微生物可以利用空气中的氮气作为氮源若要设计实验进一步确定甲乙菌能否利用空气中的氮气作为氮源请简要写出实验思路预期结果和结论即. 4该小组将人工合成的一段DNA转入大肠杆菌使大肠杆菌产生能降解W的酶酶E.为了比较酶E与天然酶降解W能力的差异该小组拟进行如下实验请完善相关内容. ①在含有一定浓度W的固体培养基上A处滴加含有酶E的缓冲液B处滴加含有相同浓度天然酶的缓冲液C处滴加三处滴加量相同. ②一段时间后测量透明圈的直径.若C处没有出现透明圈说明若AB处形成的透明圈直径大小相近说明.
已知向量==﹣3则向量在向量方向上的投影为
如图所示的函数图象对应的函数解析式可能是
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