有關a12.的精選大全

已知數列{an}滿足an+1=λan+2n(n∈N*,λ∈R),且a1=2.(1)若λ=1,求數列{an}的通...
問題詳情:已知數列{an}滿足an+1=λan+2n(n∈N*,λ∈R),且a1=2.(1)若λ=1,求數列{an}的通項公式;(2)若λ=2,*數列{}是等差數列,並求數列{an}的前n項和Sn.【回答】【考點】8H:數列遞推式;8E:數列的求和.【分析】(1)當λ=1時,,由此利用累加法能...
(CNN)----A12-year-oldgirlwhohadafellingthatshemightbequ...
問題詳情:(CNN)----A12-year-oldgirlwhohadafellingthatshemightbequitecleverhastakenatestandprovedshewasabsolutelyright.LydiaSebastianachievedthetopscoreof162onMensa,sCattellIIIBpaper,suggestingshehasahigher...
等差數列{an}滿足:a4+a6+a8+a10+a12=20,則a9﹣=(  ) A.1B.2C.3D.4
問題詳情:等差數列{an}滿足:a4+a6+a8+a10+a12=20,則a9﹣=()A.1B.2C.3D.4【回答】B考點:等差數列的*質.專題:計算題;等差數列與等比數列.分析:在等差數列{an}中,由a4+a6+a8+a10+a12=20,能求出a8,再由a9﹣=(a8+d)﹣(a8+2d)=a8,能求出結果.解答:解:在等差...
已知Ba(AlO2)2可溶於水。右圖表示的是向A12(SO4)3溶液中逐滴                  ...
問題詳情:已知Ba(AlO2)2可溶於水。右圖表示的是向A12(SO4)3溶液中逐滴                  加入Ba(OH)2溶液時,生成沉澱的物質的量y與加入Ba(OH)2的物質的量x的關係。下列有關敍述正確的是A.a-b時沉澱的...
 AndrewHolleman,a12-year-oldboy,lovedplayingintheopenla...
問題詳情: AndrewHolleman,a12-year-oldboy,lovedplayingintheopenlandnearhislandwaswetandforested,andmadeahomeforbirds,otheranimalsandmanydifferentplants. Itmadetheperfectplaceforhimtostudyandgettoknowt...
已知在等差數列{an}中,a7+a9=16,a4=1,則a12的值是A.15   B.30          ...
問題詳情:已知在等差數列{an}中,a7+a9=16,a4=1,則a12的值是A.15B.30          C.31D.64【回答】解析由等差數列的*質得a7+a9=a4+a12,因為a7+a9=16,a4=1,所以a12=15.故選A.*A知識點:數列題型:選擇題...
下列計算正確的是   A、a3•a4=a12     B、(a3)4=a7  C、(a2b)3=a6b3   ...
問題詳情:下列計算正確的是   A、a3•a4=a12     B、(a3)4=a7  C、(a2b)3=a6b3    D、【回答】C知識點:(補充)整式的除法題型:選擇題...
A12-year-oldboynamedTimBrowngotlostinthemountains.Howev...
問題詳情:A12-year-oldboynamedTimBrowngotlostinthemountains.However,hesurvivedatlastthankstohisamazingsurvival(生存,倖存)skills.OnedayinOctober2016,Tim wenthikingwithhisgroupintheMagaliesbergMountains,So...
觀察下列各式:a+b=1,a2+b2=3,a3+b3=4,a4+b4=7,a5+b5=11,…,則a12+b1...
問題詳情:觀察下列各式:a+b=1,a2+b2=3,a3+b3=4,a4+b4=7,a5+b5=11,…,則a12+b12=A.521                                 B.322C.123                                 D.1...
設等差數列{an}的前n項和為Sn,且a2+a7+a12=24,則S13=(  )A.52          ...
問題詳情:設等差數列{an}的前n項和為Sn,且a2+a7+a12=24,則S13=()A.52                              B.78C.104                             D.208【回答】C知識點...
下列計算:(1)an•an=2an,(2)a6+a6=a12,(3)c•c5=c5,(4)26+26=27,(...
問題詳情:下列計算:(1)an•an=2an,(2)a6+a6=a12,(3)c•c5=c5,(4)26+26=27,(5)(3xy3)3=9x3y9中,正確的個數為()A.0個 B.1個  C.2個 D.3個【回答】B【考點】冪的乘方與積的乘方;合併同類項;同底數冪的乘法.【分析】根據同底數冪的乘法的*質,合併...
完形填空XiaoQiang,a12-year-oldChineseboy,hastoomanyactiviti...
問題詳情:完形填空XiaoQiang,a12-year-oldChineseboy,hastoomanyactivities.Hisfather  1_  himawayfromschoolfourafternoonsaweekanddriveshimacrosstowntopractice.“Idomostofmy  2  inthecarwhenweare_3...
已知數列{an}為等差數列,且a1+a7+a13=4π,則tan(a2+a12)的值為(  )(A) (B)-...
問題詳情:已知數列{an}為等差數列,且a1+a7+a13=4π,則tan(a2+a12)的值為()(A) (B)- (C)± (D)-【回答】B.因為a1+a7+a13=4π,所以a7=,tan(a2+a12)=tan=-,故選B.知識點:數列題型:選擇題...
已知等差數列{an}中,a7+a9=16,a4=1,則a12的值是(  )A.64    B.31   C.3...
問題詳情:已知等差數列{an}中,a7+a9=16,a4=1,則a12的值是(  )A.64    B.31   C.30    D.15【回答】D知識點:數列題型:選擇題...
下列運算中正確的是(    )A.a3-a2=a       B.a3·a4=a12        C.a6÷...
問題詳情:下列運算中正確的是(    )A.a3-a2=a       B.a3·a4=a12        C.a6÷a2=a3           D.(-a2)3=-a6【回答】D知識點:整式的乘法題型:選擇題...
下列計算中,正確的是(   ). A.a+a11=a12       B.5a-4a=a          C...
問題詳情:下列計算中,正確的是(   ). A.a+a11=a12       B.5a-4a=a          C.a6÷a5=1          D.(a2)3=a5 【回答】B;知識點:各地中考題型:選擇題...
下列運算中,結果正確的是(▲)A.a3•a4=a12  B.a10÷a2=a5    C.a2+a3=a5  ...
問題詳情:下列運算中,結果正確的是(▲)A.a3•a4=a12  B.a10÷a2=a5    C.a2+a3=a5D.4a-5a=-a【回答】D 知識點:整式的乘法題型:未分類...
用含有A12O3、SiO2和少量FeO·xFe2O3的鋁灰製備A12(SO4)3·18H2O。,工藝流程如下(...
問題詳情:用含有A12O3、SiO2和少量FeO·xFe2O3的鋁灰製備A12(SO4)3·18H2O。,工藝流程如下(部分*作和條件略):Ⅰ.向鋁灰中加入過量稀H2SO4,過濾:Ⅱ.向濾液中加入過量KMnO4溶液,調節溶液的pH約為3;Ⅲ.加熱,產生大量棕*沉澱,靜置,...
在正項等比數列{an}中,a1和a19為方程x2-10x+16=0的兩根,則a8·a12=
問題詳情:在正項等比數列{an}中,a1和a19為方程x2-10x+16=0的兩根,則a8·a12=__________.【回答】16     知識點:數列題型:填空題...
AndrewHolleman,a12-year-oldboy,lovedplayingintheopenlan...
問題詳情:AndrewHolleman,a12-year-oldboy,lovedplayingintheopenlandnearhislandwaswetandforested,andmadeahomeforbirds,otheranimalsandmanydifferentplants. Itmadetheperfectplaceforhimtostudyandgettoknowthe...
設Sn是等差數列{an}的前n項和,a12=-8,S9=-9,則S16=(   )A.-72       B....
問題詳情:設Sn是等差數列{an}的前n項和,a12=-8,S9=-9,則S16=(   )A.-72       B.72   C.36 D.-36【回答】A【解析】由等差數列通項公式,前n項和公式可得知識點:數列題型:選擇題...
水稻的體細胞中有12對染*體,也就是包含了()個DNA分子。A12  B24  C6  D32
問題詳情:水稻的體細胞中有12對染*體,也就是包含了()個DNA分子。A12  B24  C6  D32【回答】B知識點:基因控制生物的*狀題型:選擇題...
如圖,正十二邊形A1A2…A12,連接A3A7,A7A10,則∠A3A7A10=  .
問題詳情:如圖,正十二邊形A1A2…A12,連接A3A7,A7A10,則∠A3A7A10=.【回答】75°.【分析】如圖,作輔助線,首先*得=⊙O的周長,進而求得∠A3OA10==150°,運用圓周角定理問題即可解決.【解答】解:設該正十二邊形的中心為O,如圖,連接A10O...
閲讀理解AndrewHolleman,a12-year-oldboy,lovedplayingintheope...
問題詳情:閲讀理解AndrewHolleman,a12-year-oldboy,lovedplayingintheopenlandnearhishome.Thelandwaswetandforested,andmadeahomeforthebirds,otheranimalsandmanydifferentplants.Itmadetheperfectplaceforhimtostudyan...
已知等差數列{an}中,a6+a10=16,a4=1,則a12的值是A.15            B.30 ...
問題詳情:已知等差數列{an}中,a6+a10=16,a4=1,則a12的值是A.15            B.30             C.31             D.64【回答】A知識點:數列題型:選擇題...
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