数列中常见递推关系归类剖析

新教材明确指出:数列可以由其递推关系式及前几项给定.根据递推关系求解通项,除用计算———猜想———证明的思路外,通常还可以对某些递推关系式进行变换,从而转化成等差、等比数列或易于求出通项的数列的问题来解决.下面分类说明这些常见的递推关系的类型及其解法.　一、an+1=an+d(其中d是常数)显然,由an+1-an=d知{an}是等差数列,则an=a1+(n-1)d.二、an+1=anq(其中 q是不为0的常数)显然,由an+1an=q知{an}是等比数列,于是an=a1qn-1.三、an+1=an+f(n),方法:叠加法例1 　在数列{an}中,a1=1,且an+1=an+,求an.解析 　由an+1=an+2n 得:a2-a1…     

等差与等比数列的简单推广

等差与等比数列是最基本而重要的数列。我们稍加推广,便可得到两种既包含等差数列又包含等比数列的数列。一、等比差数列通项为a_n=qa_(n-1)+d(其中q和d为常数)的数列(当d=0时为等比数列,当q=1时为等差数列),我们称它为等比差数列。     

等比差数列的性质与应用

一个首项为a_1,以后各项由递推式a_k=qa_(k-1)+d(其中q和d为常数,k≥2)确定的数列,称为“等比差数列”(当d=0时为等比数列;当q=1时为等差数列)。等比差数列的通项公式与前n项和的公式,我在本刊82年3期《等差与等比数列的简单推广》一文中已经给出:     

数列易错题分类解析

在利用数列的定义解题时出错例1有下列四个判断:①若a,b,c,d成等比数列,则a b,b c,c d也成等比数列;②若数列{an}既是等差数列又是等比数列,则{an}为常数数列;     

如何用常数列求数列的通项

在数列{an}中,若an＋1=an=a（n∈N＊,a为常数）,则称数列{an}为常数列,若a≠0,则称数列{an}为非零常数列.非零常数列既是公差d=0的等差数列,又是公比q=1的等比数列.     

关于等差等比数列性质的复习

等差、等比数列,是高中数学的重点内容,也是高考的热点重点,我们必须熟练地掌握它,下面我们复习“等差、等比数列的性质”。比较是一切理解的基础,这部分内容可比较的东西很多,下面我们就利用比较法进行这部分的复习。一、定义比较(正反比较,加深概念的理解)1.正面比较等差数列的定义:a2-a1=a3-a2=a4-a3=…=d,即an-an-1=d等比数列的定义:a2∶a1=a3∶a2=a4∶a3=…=q,即an∶an-1=q2.反面比较显然,由上面的等差数列的定义可知:一个等差数列的每一项加上同一个常数等于后项,如果一个数列的每一项加上同一个常数,都等于后一项,那么这个数列是等差…     

关于数列的模拟题

一、选择题(每小题5分,共50分)1.已知数列｛an｝是公比为q的等比数列,若bn=an 2an 2,n!N*,则数列｛bn｝是A.公比为q的等比数列B.公比为q2的等比数列C.公差为q的等差数列D.公差为q2的等差数列2.已知数列｛an｝,则“对任意的n!N*,点Pn(n,an)都在直线y=3x 2上”是“数列｛an｝为等     

递推数列在排列组合与概率中的应用

数列是高中数学的重要内容,也是高考考查的重点,特别是递推数列,在数学问题中的广泛应用越来越引起人们的重视.下面就递推数列在排列组合与概率应用题中的应用作探讨,以供参考.一、递推式为an=pan-1 q(p、q为常数且p≠1)这类数列求通项方法为构造等比数列an p-q1或{an-an-1}.例     

“MM”实验课教案:等比数列(第1课时)

1教学目标1．1掌握等比数列的定义;1．2归纳出等比数列的通项公式;1．3会解决有关通项公式的简单问题;1．4进行史志教育,激发学生学习数学的兴趣;1．5渗透数学中的类比、归纳、猜测等合情推理方法．2教学过程2．1复习（1）等差数列的定义：如果一个数列从第2项起,每一项与它的前一项的差等于同一个常数,这个数列就叫做多差数列,这个常数叫做等差数列的公差,通常用d来表示．（2）等差数列的通项公式：an-a1＋（n－1）d（3）an＝am＋（n－m）d（n＞m）（4）若m＋n=p q,则am an=ap aq（详细板书,为展开新课作准备）2．2引入（1）早…     

求递推数列通项的常用解法

我们把数列连续若干项之间的等量关系an+k=f(an+k-1,an+k-2,…,an)称为数列的递推关系.由递推关系和k个初始值可以确定一个数列,称数列{an}是递推数列.(如:等差数列满足an+2=2an+1-an是二阶线性递推数列,等比数列满足an+1=qan是一阶线性递推数列)     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…