填空题二次型f(x 1 ，x 2 ，x 3 )=(x 1 +x 2 ) 2 +(x 2 一x 3 ) 2 +(x 3 +x 1 ) 2 的秩为_________．

填空题二元函数z=x2+3xy+y2+2x，则=______．

填空题设总体X～E(λ)，则来自总体X的简单随机样本X 1 ，X 2 ，…，X n 的联合概率密度f(x 1 ，x 2 ，…，x n )=_________．

填空题设f(x)二阶可导且满足则f(x)=______。

填空题设，则常数a=_____.

填空题[A]Thetake-upofEVs—whichrunentirelyonelectricitystoredinrechargeablebatteries—isseenascentraltotheplantocutthetransportsector'scarbonemissions,bothhereandacrosstheEuropeanUnion.Itispredictedthatwewillberunningatotalof800,000EVsinBritainby2020,andasaresulttheracetoinstallarecharginginfrastructureiswellunderway.TransportforLondon(TfL)recentlyannounceditwillhave1,300EVchargingpointsinLondonby2013—morethanthecurrentnumberofpetrolstationsinthecapital.TheLondonmayor,BorisJohnson,isontherecordassayinghewantstomakethecitytheelectriccarcapitalofEurope.[B]However,thepowercompanies,sensingagoodbusinessopportunity,arenowvyingtosignupelectriccar-owninghouseholdswiththeofferofcheaperandfasteroff-peakhomechargingthatwillcutthetimeittakestorechargethevehicle—freeingittomakemorejourneys,andmakingthemmoreattractivetobuyers.Sofar,EDF,BritishGas,andmostrecentlynpowerhavesaidtheywillbetargetingEVuserswithspecialhomeservicesaswellascheapertariffsforrechargingvehicles.[C]Whatwouldmakeyouconsiderbuyinganelectriccar?Theyofferagreenwaytogetaround,withthechancetobypasspetrolstations.AndtheyareexemptfromroadtaxandLondon'scongestioncharge.Energycompanynpower(英国电力公司)thisweekrevealedthat33%ofUKdriverswouldthinkaboutbuyinganelectricvehicle(EV)inthenextfiveyears,risingto41%whenthebenefitswereexplained.[D]ButdespitetheintroductioninJanuaryofagenerous￡5,000governmentpurchasegranttoencouragemorepeopletotaketheplunge,it'sfairtosaythatsalesofelectricallypoweredcarsintheUKareyettoreallytakeoff.Justover500peopletookthegovernmentuponitsofferinthefirstquarterofthisyear.Theirhighprices—typicallyabout￡25,000afterthegrant—plusalackofmodelsbymajorcarmakersandashortageofchargingpoints,haveheldbacksales.However,thelasttwopointsareabouttochange.[E]SpeakinginBerlinlastweek,npower'sheadofe-mobility,PhilEvans,toldGuardianMoneythatthecompanyseesEVsasamajoropportunity,andasaresultitisworkingonbuildingan"upgradable"charginginfrastructurethatwilldevelopasthecars'powersystemsbecomemoresophisticated.[F]PotentialbuyersnowhaveachoiceofsevenmodelsintheUK,with13moreontheway,whileEDFEnergy(英国电网),BritishGasandnpowerhaverecentlyannouncedplanstostartofferingtoinstallfasterandcheaperchargingpointsincustomers'homes,inamovetheyhopewillhelpkick-startsales.Thecompaniesarebankingonthefactthatbuyersofthelatest,moreconsumer-friendlyelectriccars,suchastheNissanLeaf,aregoingtoboostdemandforelectricity.[G]PlansarealsounderwaytoincreasethenumberofchargingpointsatavarietyoflocationsacrosstheUK—andsoonitwillbepossibleforhomeownerstoupgradetheirgaragestoallowfaster,saferhomecharging.Untilrecently,mostownersofplug-in-to-rechargeelectriccarshavehadtorelyonthetraditionalthree-pointhouseholdplug,andwaitabouteighthourstofullyrechargetheirvehicleathome.

填空题设随机变量X的密度函数为，若，则a=________．

填空题已知r(α 1 ，α 2 ，…，α s )=r(α 1 ，α 2 ，…，α s ，β)=m，r(α 1 ，α 2 ，…，α s ，γ)=m+1，则r(α 1 ，α 2 ，…，α s ，β，γ)=_____。

填空题设B≠O为三阶矩阵，且BA=O，则r(B)=________．

填空题函数z=2xy-3x 2 -2y 2 +20的极______值是______．

填空题∫sec 2 5xdx=__________．

填空题求心脏线ρ=4(1+cosθ)和直线θ=0及围成的图形绕极轴旋转所成旋转体体积为________．

填空题已知∫f(x)dx=F(x)+C，则∫f(sinx)cosxdx=______。

填空题积分=______．

填空题=_______

填空题设A～B，其中，则x=________，y=________．

填空题设a＞0，a≠1，且则p=________

填空题定积分=________。