第2期2版21.2.3因式分解法1.解:(1)因式分解,得(5x+6)(5x-6)=0.于是得5x+6=0,或5x-6=0,-56(2)移项,得2x(x+2)-5(x+2)=0.因式分解,得(2x-5)(x+2)=0.于是得2x-5=0,或x+2=0,5二、填空题31x1=2=-2.s+=,s=-2(3)移项,得(x+4)2-2(x+4)=0.7.-20228.=2,x39.10%因式分解,得(x+4)(x+4-2)=0.10=2k=-511-号-P=s-4=32-4x于是得x+4=0,或x+4-2=0,x1=-4,x2=-2,12.7-V2或7或7+V2=7,即-=tVT-2=422.x-1-2=0;x1=-1,x2=3三、解答题*21.2.4一元二次方程的根与系数的_1=s=V7.13.解.(1)移项,得3x(x-1)+(x-1)=0s t st关系因式分解,得(x-1)(3x+1)=0.:的值为V7或-V71.C于是得x-1=0,或3x+1=0,2.53.25x1=1,x2=-34解:设方程的另一根为x2,且x=4.(2)移项,得(x+3)2_(1-2x)2=0.根据根与系数的关系,得x+x2=4,因式分解,得(x+3+1-2x)(x+3xx2=1-m,1+2x)=0,即4+x2=4,4x2=1-m.即(-x+4)(3x+2)=0.解得x2=0,m=1.于是得-x+4=0,或3x+2=0所以m的值为1,另一个根为0.25.解:(1)根据题意,得△=(2m)2-x1=4,x2=-3·4(m2+m)≥0.14.解:设每个人转发x个好友解得m≤0.根据题意,得1+x+x2=157.(2)根据一元二次方程根与系数·解得x=12x=-13(不合题意,舍去)】的关系,得x1+x2=-2m,xx2=m2+m.答:每个人转发12个好友15.解:答案不唯一,如x2+x2=(x1+2)2-2x12=12,.(-2m)2-2(m2+m)=12,即m2-m-②利用因式分解法:x2-3x=0.因式分解,得x(x-3)=06=0.于是得x=0,或x-3=0,解得m=-2,m2=3(舍去).故m的值为-2.x1=0,x2=3.③利用配方法:x2-4x=4,21.3实际问题与一元二次方程配方,得x2-4x+4=8,第1课时(x-2)2=8.1B2解:(1)设该校这两年藏书的年·由此可得x-2=±2V/2,均增长率为x.x1=2+2V2,x2=2-2V2.根据题意,得5(1+x)2=9.816.解:(1)(36-3x).解得x=0.4=40%,x2=-2.4(不合题(2)根据题意,得x(36-3x)=96.意,舍去)解得x1=4,x2=8.答:该校这两年藏书的年均增·当x=4时,36-3x=36-3×4=24>22,长率为409%.不符合题意,舍去;(2)9.8×(1+40%)=13.72(万册).当x=8时,36-3x=36-3×8=12<22,答:预测到2023年年底该校的藏符合题意.书量是13.72万册.答:若围成的菜地面积为96方第2课时米,此时的宽AB为8米1.112.解:设每顶头盔应降价x元,则17解1)子分每顶头盔的销售利润为(68-x-40)元,(2).·一元二次方程2x2-3x-1=0均每周的销售量为(100+20x)顶.;的两个根分别为m,n,根据题意,得(68-x40)(100+20x)=31m+n=2mn=-24000.整理,得x2-23x+60=0..nmmitn_(mtn)2mnnmnmn解方程,得x1=3,x2=20,11.68-x≤58,3P-2x22113.x≥10.121.x=20.-2答:每顶头盔应降价20元(3).·实数s,t满足2s2-3s-1=3版10,22-3t-1=0,且s≠t,一、选择题.s,t是一元二次方程2x2-3x-1=01~6.ACADBA的两个实数根
第4期综上,0=2或a=2.故选BD.子4g6第23版同步周测参考答案一、单项选择题11.AD提示:因为f(x)=(m2-3)x为幂函数,所(2)原式=l0g3子+g(125x8)+2=】+3+2=以m2-3=1,所以m=-2或m=2.当m=2时,八x)=x2,此时1A提示:由lg2-1.得=hg2e3.则418解:(1)因为幂函数x)=(m2-3m+3)x是偶2)=4,函数x)的图象不过点2,4,不符合题意,2=2”9.故选A函数,所以m2-3m+3=1,解得m=2或m=1,又f八x)是偶2.C提示:因为函数y=(m2-2m-2)m是指数函故f(x)≠x2;当m=-2时,f(x)=x2,此时f2)=,函数函数,所以4m-m是偶数,则m=2,所以函数爪x)的解m2-2m-2=1,析式为爪x)=x数,所以m>0,x)的图象过点2.4,符合题意,故x)=2又-x)归(2)因为f(x)=x4在[0,+)上单调递增,在(-0解得m=3.故选C.0)上单调递减,所以f2x-1)
第3章一元函数的导数及其应用学生月书走进高考—高考真题(3)若存在a,使得f(x)≤a十b对任意x∈R成立,求实数b的取值范围.1.(2021·全国乙卷)设a≠0,若x=a为函数f(x)=a(x一a)2(x-b)的极大值点,则)A.a
学生用八书名师导学·新高考第一轮总复·数学B组题(2)若角a的终边上一点M(号,m),且OM1.设集合M=(aa=至+k·受,k∈Z,N==1(O为坐标原点),求m的值及sina{aa=90°+k·45°,k∈Z},则集合M与N的值.的关系是A.M∩N=B.M孱NC.N晏MD.M-N2.已知角a(0≤a<2π)终边上一点的坐标为(sn吾cas,则a等于61A缙Bc.3.如图所示的圆中,已知圆心角∠A0B=,半径0C与弦AB垂直,垂足为点D.若CD的长为a,则ACB与弦AB所围成的弓形ACB的面积为4已奥a=品a且g(ease有意义1(1)试判断角α所在的象限;388
基础题与中考新考法·八年级·上·数学62π(2ab+b)【解析】:大半圆的面积==2x11+)(1+1)1t2)(1+2(a+6),小半圆的面积=a2,S1》S大半圆一S小半圆=2ma22m(a+b)212m(a2+12 ma'=12ab+62)-1ma2π(a2+2ab+62-a2)==2x(121+宁12)2π(2ab+b2).7.解:(1)原式=(40-1)2=402-2×40×1+12=1521;=2(10=2(2)原式=(200+1)2+99×1013=200+400+1+(100-1)(100+1)14.2.2完全方公式=40000+400+1+10000-1课第1课时完全方公式=50400.分1.(a-b)2,a2-2ab+b2,(a-b)2=a2-2ab+b2.8.A【解析】(mx-y)2=m2x2-2mxy+y2=4x2-2.C3.1B4xy+ny2,.m2=4,-2m=-4,n=1,解得m=练3.22,-4【解析】(x+2a)2=x2+4ax+4a2=2,m=2nx2+8x-46,∴.4a=8,4a2=-4b,解得a=2,b=-4.9.解:原式=4a2-20ab+25b2-(2a+b)(2a-b)4.(1)1-2ab+a2b2;(2)4x2+12xy+9y2.罩=4a2-20ab+25b2-(4a2-b2)解:(1)原式=(分)2-2·子6+65.=4a2-20ab+25b2-4a2+b2=26b2-20ab,。ab+b2;将a=1,b=2代入得,(2)原式=[-(5m2+n)]2原式=26×22-20×1×2=64.=25m4+10m2n+n2;10.解:(1)a+b=8,ab=12,(3)原武=(分)2+2·2t,2∴.a2+b2=(a+b)2-2ab=82-2×12=40;34(3)(2)(a-b)2=(a+b)2-4ab=82-4×12=16;12.4(3)由(2)得(a-b)2=16,则a-b=±4;4x3y+(4)(a+b)(a-b)=a2-b2,(4)原式=m2-4m-(m2-2m+1).a2-b2=8×(±4)=±32.=m2-4m-m2+2m-111.解:(1)102+112=(110+1)2-(10×11)2;=-2m-1;【解法提示】观察可知12+22=(1×2+1)2-(5)原式=n2-4mn+(2m)2-[(-2m)2+4mn+(1×2)2;2+32=(2×3+1)2-(2×3)2;32+42m2]=(3×4+1)2-(3×4)2;.第10个等式为=n2-4mn+4m2-4m2-4mn-n2102+112=(10×11+1)2-(10×11)2=(110+=-8mn.1)2-(10×11)2.52万唯八年级QQ交流群:703305283
-
5.ABD解析:对于A,根据散点图知,7:00~7:30内,每分1×(-0.1)+2×(-0.2)=-1,钟的进校人数y与相应时间x呈正相关,故A正确;对于B,由图知,曲线y=0.82e.16x的拟合效果更好,故乙同学(x,-z)2=(-2)2+(-1)2+12+22=10,i=的经验回归方程拟合效果更好,故B正确;对于C,表格2(:-x)(2:-z)中并未给出对应的值,而由甲的经验回归方程得到的只则名=110=-0.1,能是估计值,不一定就是实际值,故C错误;对于D,全校(x:-x)2=1学生近600人,从表格中的数据知,7:26~7:30进校的人a=元-6元=4+0.1×2=4.2,数超过300,故D正确.故选ABD.则之关于x的经验回归方程为之=-0.1x十4.2.解析:由表中数据得x=6.5,y=80,由y=一4x十②由y=kc+20(x≥0),得y-20=kc(x≥0),两边取对数,得ln(y-20)=ln十xlnc,a,得a=106,故经验回归方程为y=一4x十106.将(4,利用①的结论,得lnc=-0.1,lnk=4.2,90),(5,84),(6,83),(7,80),(8,75),(9,68)分别代入经所以c=e.1≈0.9,k=e2≈66.7.验回归方程,可知有6个样本点,因84<一4×5+106=(2)由(1),得y=66.7×0.92+20(x≥0),86,68<一4×9+106=70,故(5,84)和(9,68)在经验回令y=60,得x=log0.g0.6≈4.8.归直线的左下方,满足条件的只有2个样本点,故所求概所以该品种绿茶用85℃的水泡制4.8min后饮用,口感率为号-号最佳.【方法导航】有些非线性回归分析问题并不给出经验公【易错分析】概率与经验回归方程相结合,不能准确求出式,这时我们可以画出已知数据的散点图,把它与学过的a导致出错.各种函数(幂函数、指数函数、对数函数等)的图象进行比7.85解折:由公,=50,得立=品2,=50×5,再由较,挑选一种跟这些散点拟合得最好的函数,用适当的变量进行变换,把问题化为线性回归问题,使之得到解经验回归方程恒过点(u,)可得,元=1.5×u+1=1.5×决.其一般步骤:5+1=8.5,所以20:=107=10X8.5=85画散i=根据原始数据(工:y)画出散点图8.解:(1)由题知i=3,5=47,2:=852√21,-i2-点图i=1选拟而√2g.-=v2278,合函数根据散点图,选择拾当的拟合函数则r=852-5×3×47147147147A√/10X2278√227802√5695150.94≈变换进行恰当的变换,转化成线性函数,0.97>0.75.求解:求线性回归方程故y与t的线性相关程度很高,可用经验回归模型拟合.变换(2)由题得=2(t:-0(y:-)还原通过相应的变换,即可得非线性回归方程1472a,-010=14.7,a=47考点52)列联表与独立性检验14.7×3=2.9.1.D解析:独立性检验假设有反证法的意味,应假设两类所以y关于t的经验回归方程为y=14.7t十2.9.变量(而非变量的属性)无关,这时的X应该很小,如果将t=6带入经验回归方程,得y=91.1≈91,X2很大,则可以否定假设,如果2很小,则不能够肯定或所以预测第6年该公司的网购人数约为91人.者否定假设.故选D,2.A9.解:(1)①由已知得出x与之的关系,如下表:解析:列2×2列联表如下:泡制时间x/min01234合计4.24.14.03.93.8yy2设经验回归方程为之=bx十a,o2131由题意,得元=0+1+2+3+4=2,355=4.2+4.1+40+3.9+3.8-4,合计10+c21+d6666×[10(35-c)-21c]2所以2(x:-x)(x:-z)=(-2)×0.2+(-1)×0.1+故X2=31×35×(10+c)56-c≥5.024.把选项代入验i=证可知A符合.故选A,八牧学笔记数学·参考答案/99
10.x+2 x751由题意得,2x60253012【解析】设甲经过x日与乙相逢,则乙已出发(x+2)解得x=50(2分)日,根据甲行驶的路程+乙行驶的路程=齐国到长经检验,x=50是原分式方程的解,且符合实际,安的路程(单位1),即可得出42,文=1.2x=10075答:走路线二的均速度为100千米/小时;…1解:(3(xD…(1分)。。。。。。(4分)(2)能,理由如下:…(5分)9-x>3(x-1);…(2分)》由题意得,该游客从酒店到达南昌八一起义纪念馆7>5<3;…(4分)所用的时间最多为25×60+10=40分钟,50753;…(5分)。。。。。(6分):8时10分+40分=8时50分,(2)C,A.(6分)12.解:(1)设走路线一的均速度为x千米/小时,则.该游客到达纪念馆的时间最晚为8:50,走路线二的均速度为2x千米/小时·.他能在南昌八一起义纪念馆开馆之前赶到…(8分)专题三函数=-4,.点(2,1)不在直线y=-2x上.基础点22函数初步1.1C础题分点练1.x≠-3【解析】>0,.y随x的增大而增大,-1<2,【解析】x+3≠0,.x≠-3.y1
对于B:了(2+x)-(-x).则函数关于x-号-1对称,故B正确:对于C:.∫(.x)的一个周期为4,∴.∫(2022)=∫(505×4+2)=f(2),令∫(2+x)=∫(一x)中的.x=0,则∫(2)=f(0),函数∫(x)为定义在R上奇函数,.∫(0)=0,∴.∫(2022)=0,故C正确;对于D:∫(x)的一个周期为4,.∫(2023)=f(506X4-1)=∫(-1),函数∫(x)为奇函数,∫(-1)=-f(1)=-2,∴.∫(2023)=-2,故D错误;故选ABC.12.BCA:f(x)=0台x-1-lnx=0,x-1≥lnx,当且仅当x=1时取等号,故A错误,C正确;B:了(x)=2x-2-1mxx)=2--2,在(03)上f(x)<0了(x)为藏函数在(日+)上(x)>0,∫(x)为增函数,又∫()>0,∫(2)<0f(1)=0,有2个零点,B正确D错误.故选BC1a宁因为y一0)=6,了0=(y-六f④)-2方片放在1=4mm时的瞬时降到强度某一时刻降雨量的瞬间变化率)为子mm/min.m2-3m-3=1,(m=4或m=-1,14.4由→m=422-5>015.∫(x)=7-cosx,令f(x)>0,解得
-
度,得到y=2sin2x+2π+2的图像,所以g(x)=2sin2x+2π+2.…8分33令g(x)=0,得x=kπ5πkeZ,…10分1因为g(x)[0,m]上有且仅有5个零点,所以53π≤m<年65π1212。…12分19.(12分)131己知函数f(x)=三x+二(a-1)x2+ax。3若f)在x=处取得极值,求∫)的单调递减躯(2)若f(x)在区间(0,2)上存在极小值且不存在极大值,求实数a的取值范围.【解析】f'(x)=x2+(a-1)x+a.…1分(1)因为f(x)在x=-处取得极值,3所以八3=0,o-10+a=0,解利e=即3…3分所以r=号〔+》-2。令f(x)<0,故-3
19.(★★)(本小题满分12分)就小★★已知函数f(x)=xlnx,g(x)=-x2十a.x-3(a∈R).20.(k★)((1)求f(x)在点(e,f(e)处的切线方程;已知函数Q)若函(2)若对于任意的x∈[,e],都有2f()≥g(x成立,求实数a的取(2)若a值范围定器得
-
-
第15期B1版Keys:(One possible version)课本链接1.In France.2.On March 253.A sports writer.4.An actor.5.Surprised.主题漫步1.Grade 82.buying something3.felt very lucky4.surprised5.a 20-dollar bill第15期B2版Keys:(One possible version)知识“串联”For Section AL.1.到…的时候;在…以前2.give sb a lift3.与…成一排4.stare at5.不相信地;怀疑地6.变成7.即将做某事8.到…末为止9.go off10.show upIL.1.by the time2.shown up3.gave me a lift4.in line withFor Section B1.costume party2.lose weight3.sell out4.最终成为;最后处于5.捉弄某人6.run out of7.查明;弄清IL.1.sold out2.lose weight3.costume party4.end up5.run out of语法点击1.1.had given2.had finished3.had prepared4.had been5.had writtenIL.1.had got2.had taken out3.had put away4.had raised写作一招鲜
2023-2024学年辽宁省县级重点高中协作体高三期中考试英语试题注意事项:1.答卷前,考生务必将自已的姓名、考生号$填写在答题卡上。2.回答选择题时,选出每小题答案后,用铅笔把答题卡上对应题目的答案标号涂黑。如需改动,用橡皮擦干净后,再进涂其他答案标号。回答非选择题时,将答案写在答题卡上。写在本试卷上无效。3.考试结束后,将本试卷和答题卡一并交回。考试时间为120分钟,满分150分第一部分听力(共两节,满分30分)做题时,先将答案标在试卷上。录普内容结束后,你将有两分钟的时间将试卷上的答案转涂到答题卡上。第一节(共5小题;每小题1.5分,满分7.5分)听下面5段对话。每段对话后有一个小题,从题中所给的A、B、C三个选项中选出最佳选项,并标在试卷的相应位置。听完每段对话后,你都有10秒钟的时间来回答有关小题和阅读下一小题。每段对话仅读一巡。1.'Why does the woman expect the tennis match?A.To watch it live.B.To see her favorite singer.C.To get the players'autograph.2.How does the woman find the essay?A.Creative.B.Terrible.C.Ordinary.3.What does the woman want to do?A.Wash in a laundry.B.Have lunch.C.Rent a room.4.Where are the speakers probably?A.In a college.B.In a street.C.In a train station.5.When did the man become a manager?A.Four years ago.B.Six years ago.C.Ten years ago.第二节(共15小题;每小题1.5分,满分22.5分)听下而5段对话或独白。每段对话或独白后有几个小题,从题中所给的A、B、C三个选项中选出圾佳选项。听每段对话或独白前,你将有时间阅读各个小题,每小题5秒钟;听完后,各小题将给出5秒钟的作答时间。每段对话或独白读两遍。听第6段材料,回答第6、7题。6.Why did Lily wake up early this momning?A.She needed to catch a flight.B.She had much work to do.C.Mary made some noise.7.What is the probable relationship betwcen the spcakers?A.Neighbors.B.Roommates.C.Workmates.听第7段材料,回答第89题。8.What was wrong with the woman last Wednesday?A.She had a headache.B.She failed to see clearly.C.She had trouble moving.9.How does the woman feel about the man?A.Funny.B.Kind-hearted.C.Patient.英语试题第1页(共8页)
-
This made a good home for bats,and soon the bridge was the home of thousands of bats.38 Now,they have come to val- ue their winged neighbors.The bats are a tourist attraction,and they eat lots of bugs every night. There are also structures built with the aim of bringing wild- life into the city.The Beijing Olympic Forest Park is a good ex- ample.The park used native plants and created open,natural spaces for wildlife.The result is a zone in Beijing with over 160 species of birds.In many ways,the park is the opposite of a zoo. 39 If we learn to share our space,we can become better neigh bors to the wildlife around us.40 Our own future will be en- dangered too.
【答案】 One possible version: Dear Peter, I have some good news to tell you that a bookstore nearby our school was opened.So I can't wait to invite you to visit it with me tomorrow.How about meeting at 10 am at the school gate?Is it convenient for you? The newly-opened bookstore is really unique.Not only can we purchase books but also we can get e-books for free.There is also a coffee shop inside,where we can read books joyfully. More information about the discount of the books will be sent to your email box later. Looking forward to your early reply. Yours sincerely, Li Hua
C.The bright future of Al in song writing. D.The wide application of algorithms in Al. 14.What can we infer from the last paragraph? A.Al is mainly used in writing lyrics. B.AI can take the place of instruments. C.AI will likely change how art is made. D.Al will be the major tool for art creation.
60.Yes,(I agree).Perseverance is important /crucial to suc- cess. Or:It depends.Perseverance may keep us going in a wrong direction when we remain stubborn.
M:Yes,please,Taylor.Where are you going?The Jungle Cafe? W:No.I'm going outside.There's a coffee truck in the parking lot, M:OK.Can I have a cappuccino,please? W:Sure.Do you want regular or non-fat milk? M:Regular with sugar,please.I'm not on a diet. W:OK.But Linda wants non-fat milk in her coffee. (Text 7) M:Hi,Rachel,what are you doing tomorrow? W:I'm going on a mountain hike.Why do you ask? M:I wanted you to take care of my dog while I'm at school. W:You go to school on Saturdays? M:Well,I have to take a subject test.If I pass with a good
If you are lucky granted an interview for volunteers,I can meet you at the airport and put you up with in my house.Also,I will provide you with some other help you need.Wished you good luck!
2023-2024学年考试报·高考数学文科专版答案专页9月第9-12期②名校统考显然不成立.所以m<0,则这四个数按从小到大排列构成等差数1.A解析:因为a,=2+2n-1,所以前n项和S=2(1-2")1-2列是于点霄3时,公止2,2于1112m-1+1-22-2,所以前10项和S62"+102-2-2146,故选:A2-1220解标21)l20解:1)=mn=(-(V万i,m归0T6+1013=2I2.C解析:由cos2C-2cosA-2cosB=2V3 sin Asin B-3,可1-2+1013=104又n>7+08恒成立整致a的最小得2simA+2simB+cos2C=1+2V了sin Asin B.,化简得simA+sin'B-sin(sinC=V3 sin Asin B.由正弦定理,得a+b2-c2=V3b.由余弦值为1024.故选:C定理,得sG+6V令冰m≤宁+≤2+eZ,可得4≤2T3.D解析:由log,4=n+log3,可得a=3x2”,故可得4,.是首2ab 2,由于0c<,故c-石由余弦定项为12,公比为4的等比数列,,+,+。+…+a0为数列{a,n的前=7,c=V710项和.则51214户-4-4故选:D理,得e-0+b-2 cC=3+16-2x4xV3xY52面数稀单调造猫区间为。行+子1eZ1-4设△ABC的外接圆半径为R,则由正弦定理,得2R=4.8解析:由S+2Sn2=3S.1,得S-S.=2(Sn-Sn2),所以a,=sinC 122ac2ac2a22a,即4=2(n≥3】,所以4,=4x2=1x2-8故答索为:8.(当且仅当c时,等号成立),a-1=2V7,∴.R=V7,故三角形△ABC的外接圆的面积S=R=7m.5.24650解析:当n=1时,4,=S,=9;当n≥2时,a.=S.-S13.2解析:由已知得2a-b=(3,n),且(2m-b)b=0.n2-3=21=10n-n2-[10(m-1)-(m-1)2]=-2n+11,当n=1时也满足,所以a0n=3a=1+n2=4lal=2.故B的取值范围为1,Y?+1】=-2n+11(neN*).所以当n≤5时,a>0,b=a.;当n>5时,a,<0,b,14.n+n解析:由题中数表可知,第n行中的项分别为n,2n,2=-a,所以T=S=10x4-42-24,T0=S,-46-4,-…-a0=2S,-Sw=2x3n,…,组成一等差数列,设为a,则a,=n,d=2n-n=n,所以a=21解:(1)由题意得,a=2,4=2+c,a,=2+3c(10x5-5)-(10x30-30)=650.故答案为:24,650.n+nn=n+n,即第n行第n+1列的数是n'+n.a,4,a,成等比数列,.(2+c)=2(2+3c).15.2解析:由a,-a,=8,可得公差d=4,再由a+a,=26,可得a,解得c=0或c=2.第12期高考数学(文科)月考卷(三)】1,故5=nt2na-10-2n2-,六72”-2上,要使得7≤,c≠0,c=2(2)当n≥2时,由于a-a,=c,4,-,=2c,…,a,-a1=(n-1)c,1.C解析:a,是a,与a的等比中项,.a。=a,a,=4x6=24,∴.=±2V6只需M≥2即可,故M的最小值为2.2c.2.A解析:由20+0+0元=0,得0i+0元=-20,又因为0成16.15解析:在△BDC中,由余弦定理知cos∠CDB=又a,=2,c=2,+0心=20i,所以Ad=0iBD+CD2-Bc2202+212-31212BD·CD2×20×21sin∠DB=4V37故有a=2+n(n-1)=n-n+2(n≥2,且neN*)】3.C解析:如图所示,∠A0C=45°,.设C(x,-x),则0心=(x,-x).sn∠ACD=n(∠cDB-号sin∠cDBa号ws2c0Bn号当n=1时,上式也成立,↑y.a,=n-n+2(neN*).ADCDB14,在△ACD中,由正弦定理知5V3n'e"1421-=15.故此时轮船距港口还有15 nmile.V3又,A(-3,0),B(0,2).0元=A0+(1-A)0i=(-3A,2-2A),2u30-号17解由A行-6bc及正弦定理。2T=0(42x2+4m-224a-D宁”24.A解析:2b=a+c,且a-b=4,.b-c=4,即a=b+4,c=b-4,可得sinA=sinB+sinC+sin Bsin C,于是由余弦定理可得6-4)+6-(6+4,解得6=101I3sininCtsin Bsin C-(sinin C)in BsinC.02.得11-(1-2”22(b-4)b22.解:根据题意,f(x)=4 sin xcos x+4V3sinx-2V3标折由8斯以4得-音所又snB4inG=1…inBinG子,从而inB=i血G-22m2x-2V3m2-42.-号以a,=24选择①:(2c+b)cosA+aosB=0,6.B解析::3a+mb+7c=0,.3a+mb=-7c,.(3a+mb)=18解:如图所示,A产A市+D市由正弦定理,得2 sin Ccos A+sin Acos B+sin Bcos A=0,(-7e.化简得9+m46nab-9又ab=aibs60=行.m+.∴2 sin Ccos A=-sinC,又sinC≠0,3m-40=0,解得m=5或m=-8.s4-7,又1e0,mA-7.C解析:由题意得c=2a,b2-ate2-2acc0sB=a+(2n2-2选择②:sinB+sinC-simA+sin Bsin C=0,由正弦定理,得影+c2-a2=-bc,41×hxTY西所6-2由余滋定理,得4-4又D,E分别为AB,BC的中点,且DE=2EF8.A解析:la-b1=V(a-b)'=1Va2+b-2ab=V3,设向量a又4e0a4-与a-b的夹角为0,则es=4:(a-b).2-1V3,又0∈lal-la-bl 2xV3 2选释3640.1,所以e若又B心=At-AB由面积公式以及余弦定理,可得2成(+花(a心emAy5x兮cem4.从面umA-V5,39C解析:由3a=3a,-2,得a,,所以a是等差数45又4e0m4花破衣诚故不论哪个件有=10.C解析:设等比数列a,的公比为q,则b-b=ga又Ai=AC=1,∠BAC=60°gagg9(常数6,为等差数列,设其公老为d,68-号子x1x1k分-日又a号2vs.42=8故2b+c=8ainB4sinC-8anB4sml霄-B)-6inB+2V3,19.解:(1)a,=1,a,=0+2,∴g-9-2=0,9=2或q=-1,se2Baa3s≤2.9>09=2a-=2o B-inB),b的前11项为正,第12项为零,从第13项起为负,∴S5最大且S1=S12=132.11.D解析:若m>0,则这四个数按从小到大排列构成等差(2).a=.∴sm(B+)e(7,1).2h+ee(2V3,4V5),数列是于时,公-S-S.11s5=b.55b.=ss.8.5故2b+的取值范围是(2V3,4V3).答案专页第4页
from that,such factors as lack of active exercise and bad living habit also contribute to obesity.
30.What can replace the underlined phrase in the last paragraph? A.With more time. B.With more assistance. C.More accurately. D.More passionately. 31.What can be the best title of the text? A.Open monitoring meditation helps remove errors B.Open monitoring meditation helps detect mistakes C.Open monitoring meditation helps change your perform- ance D.Open monitoring meditation helps improve your mental health
was about to go back to my house.I got into a taxi and told the driver my destination.To my surprise,the driver made an apology,says he didn't know the way.What come a taxi driver didn't know the way?I was a little of angry.At the moment,an old couple walked up and wanted to share the car.Their destina- tion was the same as me,so he let them in.The two greeted us but the grandpa told the driver the way.From their conversation I knew the driver has been a taxi driver just for three days.He


2试题)

1试题)