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若，均为非零向量，则•＝||||是与共线的（ ）
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高一下学期数学《》真题及答案
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下列说法中错误的是
零向量与任一非零向量平行
零向量与单位向量的模不相等
平行向量的方向相同
平行向量一定是共线向量
设两个非零向量不共线且共线则k的值为.
非零向量a＝sinθ2b＝cosθ1若a与b共线则tanθ－＝________.
命题零向量与任意向量共线的否定为
在以下3个命题中真命题的个数是①三个非零向量abc不能构成空间的一个基底则abc共面②若两个非零向量
0
1
2
3
在如图所示的方格纸中向量abc的起点和终点均在格点小正方形顶点上若c与xa+ybxy为非零实数共线则
设ab是两个不共线的非零向量若a与b起点相同t∈R.t为何值时atba＋b三向量的终点在一条直线上
已知非零向量a和b不共线.1若=a+b=2a+8b=3a-b求证A.B.D.三点共线2若ka+b和a
在下列判断中正确的是①长度为0的向量都是零向量②零向量的方向都是相同的③单位向量的长度都相等④单位向
①②③
②③④
①②⑤
①③⑤
以下说法错误的是
零向量与任一非零向量平行
零向量与单位向量的模不相等
平行向量方向相同
平行向量一定是共线向量
命题零向量与任意向量共线的否定为__________________________________
非零向量不共线使共线的k=___________
设ab是不共线的两个非零向量.1若=2a-b=3a+b=a-3b求证A.B.C.三点共线2若8a+k
设两个非零向量a与b不共线.1若＝3a－b.求证A.B.D.三点共线2试确定实数k使ka＋b和a＋k
非零向量不共线使共线的k=___________
下列说法不正确的是
向量的模是一个非负实数
任何一个非零向量都可以平行移动
长度不相等而方向相反的两个向量一定是共线向量
两个有共同起点且共线的向量终点也必相同
以下说法错误的是
零向量与任一非零向量平行
零向量与单位向量的模不相等
平行向量方向相同
平行向量一定是共线向量
若ab是两个不共线的非零向量a与b的起点相同则当t为何值时atba＋b三向量的终点在同一条直线上
若ab均为非零向量则a·b＝|a||b|是a与b共线的
充分不必要条件
必要不充分条件
充要条件
既不充分也不必要条件
已知两个非零向量e1e2不共线若ke1+e2与e1+ke2也不共线则实数k满足的条件是
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关于一定量的气体下列说法正确的是
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7.5分Itseemsthatthenewsindustryhasoneprimaryfocuskeepingpeopleuptodateonthestoriesofthemomentprovidingthebestinsightintoeveryinstancewherethereaderscan'tbetherethemselves.Decadesagothismeantwhennewsbrokejournalistsscrambledtocoveritdeliveringthekeyfactsanalysisandinsight.Theytoldtheiraudienceswhattheyneededtocareaboutandwhatthejournaliststhoughtwasimportant.AllofthisarrivedonyourdoorstepwiththedeliveryofthemorningpaperorwassqueezedintoanhouroflocalandnationalnewsonyourTV. Butwhilethegoalsofanewsorganizationremainthesameastheywereintheheyday全盛时期ofWalterCronkiterevolutionaryforcesbehindthesceneshavefundamentallytransformedtherelationshipthatreadershavewiththenews. Asthenewsmovesfrominktoscreensandthemobileplatformbecomestheforcetobetakenseriouslyjournalistsandthepublicationsthatsupportthemarefacedwithnewchallengesthatextendwellbeyondgatheringthetopstoriesoftheday.Asourdigitalworldexpandsouroptionsfornewsbasedonthefocuswritingstyleviewpointanddesignpublishersarefacedwiththebalancingactofmaintainingthereputationasatrustednewssourcewhiledevelopingnewincentives动机inordertoensuretheirreadership. Whilethenegativeshavebeenwelldocumentedthisongoingevolutionhasalsoresultedinamajorstepforwardforthefutureofjournalism.Ithasforcednewsbrandstolistentotheiraudiencesandbeginaconversationthatforsolongwasone﹣sided.Afterallthewebisopenfordiscussionshouldn'tourjournalismbeaswell? Readersshouldfeelempoweredtonotonlyjointheconversationaboutthenewsbutalsojoinintheeffortoftellingthewholestory.Notonlyareourmobilephonesasourceforustowatchandreadthetopstoriesthey'realsonews﹣gatheringdevicesthatempowercitizenjournaliststofillintheblanksandprovideacomprehensivepictureofthenewslandscape. 1Whatdoestheauthorthinkofthenewsindustryinthepast? A.Therewasnoeasyaccesstonews. B.Journalistsdidn'toftencommentonnews. C.Journalistswereimportantindeliveringnews. D.Publishersdidnotcareaboutreadersthatmuch. 2Thechallengesthatpublishersarefacednowarecausedby. A.people'sdecreasinginterestinnews B.moreoptionsavailablefornews C.alackofideasfornewincentives D.abadreputationofthenewsindustry 3Whatdoesthetextmainlytalkabout? A.Readersshouldbesensitivetonewsaroundthem. B.Readersshouldtakeadvantageofthemobileplatform. C.Readersdon'thavetorelyonjournalistsfornewsnow. D.Readersnowcangetinvolvedintheprocessofdeliveringnews.
3分很显然你应该为你的不守信用向她道歉.obvious
15分Flyingcarsmaysoonbecomea1real.TherideshareserviceUberhasasked2expertfromNASAtheAmericanspaceagency3helpthecompanydevelopcarsthatcanfly. Uberplanstouseflyingvehicles4thefuturetoavoidtrafficinandaroundcities.Thecompanywantstousesmalltotallyelectricaircraft5couldtakeoffandlandlikeahelicopterontopofparkinggarages.Ubersaiditsflyingvehicleswouldbemuch6quietcostlesstooperateandproducelesspollutionthanhelicopters. OnepersoninSanFrancisco7writeonTwitterIusedtothinkflyingcarswasaridiculousidea.8IchangedmymindthismorningwhenIsatinheavytraffic.AnotherpersonaddedfromMumbaiIndiaI'mreadingaboutUber9hireaNASAengineertobuildflyingcarswhileI'mstuckintraffic.Thereishope. Theexpertpredictstherewillbeseveralearlymodelsofflyingcarsthatcan'tfly10theybutwithhumanpilotswithinonetothreeyears.
3分令我们欣慰的是很多保护区正在被建造以保护濒临灭绝的野生动植物免于被猎杀.reliefendangerprotect…from
如图所示A为地球赤道表面的物体B为环绕地球运行的卫星此卫星在距离地球表面的高度处做匀速圆周运动且向心加速度的大小为a已知地球同步卫星的轨道半径为6.6RR为地球的半径引力常量为G．则下列说法正确的是
下列核反应属于人工转变的是
根据临床经验部分药物在体内的代谢也有与原子核衰变相似的规律．药物的血浆半衰期是指药物在血浆中的浓度下降一半所需的时间．某种药物的血浆半衰期为2小时一次合理剂量的用药后药物在血浆中的浓度为20毫克/升若血浆中的药物浓度下降至3毫克/升以下就要补充用药．则该药物的用药时间间隔
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