已知等差数列{an},其前n项和为Sn,若a1+a3=10,S5=35.(1)求数列{an}的通项公式;(2)若数列{bn}满足:a1b1+a2b2+a3b3+···+anbn=1+(2n-1)2n,求数列(1/(a_n⋅(log_2b_(2n+1)))的前n项和Tn. 相关知识点: 试题来源: 解析 (1)a_n=2n+1 (2)T_n=n/(6n+9) 【分析】(1...
已知Sn是等差数列{an}的前n项和,a2=5,S5=35,{bn}是等比数列,b1+b3=10,b4=9b2>0.(1)求数列{an}和{bn}的通项公式;(2)设Tn
脚长:an(mm) 220 225 230 235 240 245 250 255 260 265 鞋码:bn 34 35 36 37 38 39 40 41 42 43试用含有脚长:an的式子表示鞋码:bn的计算公式为: bn=0.2an-10 答案解:由题意,脚的长度与鞋号是一次函数关系,满足an-220=5(bn-34),解析式为bn=0.2an-10,故答案为:bn...
an+an+2 2<an+1;②存在实数M,使an≤M.(n为正整数)(Ⅰ)在只有5项的有限数列{an}、{bn}中,其中a1=1,a2=2,a3=3,a4=4,a5=5;b1=1,b2=4,b3=5,b4=4,b5=1;试判断数列{an}、{bn}是否为集合W中的元素;(Ⅱ)设{cn}是各项为正数的等比数列,Sn是其前n项和, c3= 1 4, S3= 7 4,试证明...
HMRC HIGHLIGHTS £35bn 2009/10 TAX LIABILITIES.The article deals with a report by Her Majesty's Revenue & Customs (HMRC) concerning the decreased tax gap in Great Britain for 2009 and 2010, which was estimated to be around 7.9 per cent of liabilities....
已知等差数列{an},其前n项和为Sn,若a1+a3=10,S5=35.(1)求数列{an}的通项公式;(2)若数列{bn}满足:a1b1+a2b2+a3b3+…+anb
（1）∵Sn是等差数列{an}的前n项和，且a2=5，S5=35，∴a1+d＝55a1+10d＝35，解得d=2，a1=3；∴{an}的通项公式an=3+2（n-1）=2n+1（n∈N*）；又{bn}是等比数列，且b1+b3=10，b4=9b2＞0；∴b1(1+q2)＝10q2＝b4b2＝9q＞0，解得q=3，b1=1；∴{bn}的通项公式bn=1×...
已知数列{an}是首项为2,公差为1的等差数列,{bn}是首项为1,公比为2的等比数列,则数列{abn}前10项的和等于( )A. 511B. 512C. 1023D. 1033
【题目】如图,M是△ABC的边BC的中点,AN平分∠BAC,BN⊥AN于点N,延长BN交AC于点D,已知AB=10,BC=15,MN=3 (1)求证:BN=DN; (2)求△ABC的周长试题答案 在线课程 【答案】解:∵三角形ABCD是矩形. ∴∠ABC=∠BCD=90°. ∵△PBC和△QCD是等边三角形. ∴∠PBC=∠PCB=∠QCD=60°. ∴∠PBA=∠ABC-...
10 দিনের আবহাওয়া-Bao'an District, কুয়াংতুং, গণচীন ১০:২৮ CST থেকে শুরু করে আজ 31°/26° 21% বুধ ১৪ | দিন 31° 21% আংশিক...