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设{an}是等比数列,且a2a4=a5,a4=27,则{an}的通项公式为 .
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高三下学期数学《》真题及答案
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对任意等比数列{an}下列说法一定正确的是
a
1
,a
3
,a
9
成等比数列
a
2
,a
3
,a
6
成等比数列
a
2
,a
4
,a
8
成等比数列
a
3
,a
6
,a
9
成等比数列
在等差数列{an}中已知a1=3a4=121求数列{an}的通项公式2数列{bn}为等比数列且b1=
公比为2的等比数列{an}的各项都是正数且a3a11=16则a5等于
1
2
4
8
已知等差数列{an}满足a4=6a6=10.1求数列{an}的通项公式2设等比数列{bn}的各项均为
若等比数列{an}满足a2a4=则a1a5=.
设Sn是数列{an}的前n项和若n∈N+是非零常数则称数列{an}为和等比数列.若数列{}是首项为2
已知等差数列{an}满足a1=2且a1a2a5成等比数列.求数列{an}的通项公式.
已知公差不为0的等差数列{an}的前n项和为SnS3=a4+6且a1a4a13成等比数列.Ⅰ求数列{
设则数列成
等差数列
等比数列
非等差也非等比数列
既等差也等比数列
等比数列{an}中|a1|=1a5=-8a2a5>a2则an=
(-2)n-1
-(-2)n-1
(-2)n
-(-2)n
已知{an}是等比数列a4·a7=-512a3+a8=124且公比为整数则公比q为
2
-2
-
等比数列{an}中|a1|=1a5=-8a2a5>a2则an等于
(-2)n-1
-(-2)n-1
(-2)n
-(-2)n
设2a=32b=62c=12则数列abc成
等差数列
等比数列
非等差也非等比数列
既等差也等比数列
在等比数列{an}中a2a3=32a5=32.1求数列{an}的通项公式;2设数列{an}的前n项和
设数列{an}是首项为1公比为-2的等比数列则a1+|a2|+a3+|a4|=.
等比数列共有偶数项且所有项之和是奇数项之和的3倍前3项之积等于27求这个等比数列的通项公式.
在等比数列{an}中若a1=a4=4则公比q=;a1+a2++an=.
在等比数列{an}中an>0且a1+a2=1a3+a4=9则a4+a5的值为
16
27
36
81
等比数列{an}的前n项和为Sn已知S3=a2+10a1a5=9则a1=.
已知等比数列{an}的公比q为正数且2a3+a4=a5则q的值为
2
3
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Wildlifehasbeengreatlythreatenedinthemodernage.Therearespecies物种thatare1everyday.Thewhite﹣napedcraneisatypicalexample.Soscientistsaretryingtheirbestto2thespeciesfromgoingoutofexistence. ChrisandTimworkatazoohelpingendangeredcraneswiththeir3.Emmaafemalecranehasbeenintheir4sinceshearrivedin2004. BornataninternationalcranefoundationEmmawas5byhumancaretakers.Thisledtoanunexpected6thoughshehadawonderfultimethere.Emmahad7takenherselfasacraneandbecomedeeplyattachedtohumans.She8tolivewithmalecranesandevenhada9forkillingsomeofthemwhichmadeit10forhertobecomeamother. 11thetwozookeepersdidn'twanttoseetheextinction灭绝ofthispreciousspecies.Withtheirpatienceandeffortstheysuccessfullydevelopeda12ofartificialbreeding人工繁殖andnaturalreproduction.This13Emmatogivebirthtofivebabycranes. Thetwokeepersareproudoftheirproductivework.Butbeforetheycanbe14moreeffortsmustbemadebecausethepopulationofthecraneinthewildisonthe15andmanyotherspeciesappearheadedtowardextinction.16noteveryonehasrealizedthatwildlifehasthoughtsfeelingsandmostimportantlyequalrightstosurvive. Howcanwe17theever﹣wideninggapthatseparatesusfromotheranimals?ChrisandTimofferedusthe18:humanbeingstookitforgrantedthattheir19heldallthesolutionsbutmaybetheirheartscanbeabetter20. 1A.growing B.migrating C.competing D.disappearing 2A.ban B.save C.split D.remove 3A.abortion B.recreation C.reproduction D.administration 4A.care B.eye C.mind D.story 5A.found B.chosen C.raised D.seized 6A.bonus B.consequence C.victory D.sacrifice 7A.never B.always C.unluckily D.cheerfully 8A.liked B.refused C.decided D.hesitated 9A.gift B.skill C.concern D.reputation 10A.illegal B.inspiring C.important D.impossible 11A.Therefore B.Moreover C.However D.Instead 12A.combination B.collection C.strategy D.system 13A.forced B.forbade C.taught D.enabled 14A.defeated B.grateful C.assured D.tolerant 15A.list B.rise C.agenda D.decline 16A.Incontrast B.Afterall C.Bytheway D.Onthecontrary 17A.leave B.bridge C.open D.identify 18A.course B.excuse C.answer D.reward 19A.brains B.behaviors C.services D.projects 20A.guide B.treat C.example D.companion
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Therearealwaysthosetimeswhenthere'ssomeoneannoyingusoverandover.1Evenwhenwecanbreakitoffweneedtodoitinawaythatwon'tcausetheirangertomakethingsevenworse.Handlingpeoplewedon'tlikerequiresthatwebothbesensitivetoourownneedsandthoseofthepeoplearoundus. 1.Don'treact. Oftenpeoplewillbotheryoutogetareaction.Trytoavoidblowinguporexpressingyourdiscontentnon﹣verbally.2Ordon'tmutter嘟囔thingsunderyourbreathorelseyoumightfeedthefire.Rememberthatsilencedoesnotmakeyouweak. 3Thinkaboutthebigpicture.Gettingintoaphysicalconfrontation冲突couldcostyouyourhealthyourjoboryoureducation.Rememberwhatreallymattersandtrytoputthesesmallannoyancesinperspective. 2.4 Ifyoucanfeelaconflictcomingbringingupsomethingdifferentcanbeagoodwaytodistractsomeone.Oftenannoyingpeoplewillbeaggressivedespitebeingobviouslywrongbecausetheyseetheconfrontationasabattleofegos自我.5 Ifforexamplesomeoneisinvadingyourspacetrydirectinghimtosomethinginyoursurroundingsthatisfunnyorinteresting.Ifsomeoneispestering纠缠youwithanannoyingtopicofconversationtrytobringupsomethingelsethatyouknowwillinterestthem. A.Beflexible. B.Changethesubject. C.Don'tpretendtoignoreit. D.Don'trollyoureyesormakemeanfaces. E.Yetweoftenhavenochoicebuttodealwiththem. F.Takeafewdeepbreathsandfocusonyourbreathingtocalmyourself. G.Onceyou'vestoppedtheirangertheymightnolongerfeeltheneedtoannoyyou.
XYZM为短周期元素原子序数依次增大YM同主族X的简单氢化物遇M单质产生白烟Z的氧化物与M的氢化物不反应可与Y的氢化物反应.下列说法正确的是
抗倒酯是一种植物生长调节剂其中间产物G的合成路线如下 已知 Ⅰ. Ⅱ. Ⅱ. 请回答 1烃A中所含官能团的名称是B的结构简式为G的结构简式为. 2D为反式结构D→F反应的化学方程式为C→D反应类型为. 3同时满足下列条件的C的同分异构体有种写出它们的结构简式. ①能发生银镜反应和水解反应 ②核磁共振氢谐有两组峰峰面积之比为11 4选用必要的无机试剂设计完成B→C的合成路线用结构简式表示有机物用箭头表示转化关系箭头上注明试剂和反应条件 已知碳碳双键在加热条件下易被氧气氧化.
Nowadaysthefortravellingisshiftedfromshoppingtofoodandscenery. A.priority B.potential C.proportion D.pension
短周期主族元素XYZW原子半径依次增大W是短周期主族元意中原子半径最大的元素Z原子的核外电子数是X的两倍Z与X同主族Y与Z同周期.下列说法正确的是
Inthe1960swhilestudyingthevolcanichistoryofYellowstoneNationalParkBobChristiansenbecamepuzzledaboutsomethingthatoddlyhadnottroubledanyonebefore:hecouldn'tfindthepark'svolcano.IthadbeenknownforalongtimethatYellowstonewasvolcanicinnature﹣that'swhataccountedforallitshotspringsandothersteamyfeatures.ButChristiansencouldn'tfindtheYellowstonevolcanoanywhere. Mostofuswhenwetalkaboutvolcanoesthinkoftheclassiccone圆锥体shapesofaFujiorKilimanjarowhicharecreatedwheneruptingmagma岩浆pilesup.Thesecanformremarkablyquickly.In1943aMexicanfarmerwassurprisedtoseesmokerisingfromasmallpartofhisland.Inoneweekhewastheconfusedownerofaconefivehundredfeethigh.Withintwoyearsithadtoppedoutatalmostfourteenhundredfeetandwasmorethanhalfamileacross.AltogethertherearesometenthousandofthesevolcanoesonEarthallbutafewhundredofthemextinct.Thereishoweverasecondlessknowntypeofvolcanothatdoesn'tinvolvemountainbuilding.Thesearevolcanoessoexplosivethattheyburstopeninasinglebigcrackleavingbehindavastholethecaldera.YellowstoneobviouslywasofthissecondtypebutChristiansencouldn'tfindthecalderaanywhere. JustatthistimeNASAdecidedtotestsomenewhigh﹣altitudecamerasbytakingphotographsofYellowstone.Athoughtfulofficialpassedonsomeofthecopiestotheparkauthoritiesontheassumptionthattheymightmakeaniceblow﹣upforoneofthevisitors'centers.AssoonasChristiansensawthephotosherealizedwhyhehadfailedtospotthecaldera:almostthewholepark﹣22millionacres﹣wascaldera.Theexplosionhadleftaholemorethanfortymilesacross﹣muchtoohugetobeseenfromanywhereatgroundlevel.AtsometimeinthepastYellowstonemusthaveblownupwithaviolencefarbeyondthescaleofanythingknowntohumans. 1WhatpuzzledChristiansenwhenhewasstudyingYellowstone? A.Itscomplicatedgeographicalfeatures. B.Itsever﹣lastinginfluenceontourism. C.Themysterioushistoryofthepark. D.Theexactlocationofthevolcano. 2Whatdoesthesecondparagraphmainlytalkabout? A.Theshapesofvolcanoes. B.Theimpactsofvolcanoes. C.Theactivitiesofvolcanoes. D.Theheightsofvolcanoes. 3Whatdoestheunderlinedwordblow﹣upinthelastparagraphmostprobablymean? A.Hot﹣airballoon. B.Digitalcamera. C.Bigphotograph. D.Bird'sview.
Unliketraditionalgymsapp﹣backedgymsofferpeopleoptionstoexercise. A.casual B.regular C.flexible D.tight
theconvenienceofdigitalpaymentmanyseniorcitizensstartedtousesmartphones. A.Toenjoy B.Enjoying C.Tohaveenjoyed D.Enjoy
Theseating1arrangeisprobablythemostimportantpartofChinesediningetiquette礼仪.Moderndiningetiquetteisenacted进行发生accordingto2principles:themasterofthefeastandguests. Theseatofhonor2reserveforthemasterortheguestwiththehigheststatusistheonefacingeastortheentrance.Thoseofhigherpositionsitclosertothemaster.Theguestsofthelowestpositionsit3farfromtheseatofhonor. Ifroundtables4usetheseatfacingtheentranceisthehonorone.Theseatsonthelefthandsideoftheseatofhonoraresecondfourthsixthetc.inimportance5thoseontherightarethird6fiveseventhandsoonuntilthey7jointogether. Inancienttimestherewasakindoffurnitureknownas8EightImmortalstableabigsquaretablewithbenchesfortwopeopleonboth9side.Iftherewasaseatfacingtheentrancetherighthandseatwasfortheguestofhonor.Ifthemealwasoutsideorthereweretwoormoredoors10equalimportancethentherighthandseatwhenfacingeastwasthehonorseat.
Themusicianalongwithhisbandmemberstenperformancesinthelastthreemonths. A.gives B.hasgiven C.havegiven D.give
某课题组以纳米Fe2O3作为电极材料制备锂离子电池另一极为金属锂和石墨的复合材料通过在室温条件下对锂离子电池进行循环充放电成功地实现了对磁性的可逆调控如图.以下说法正确的是
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