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1.
在代数(必修本)下册封面上有一自然数平方和1~2+2~2…+n~2=1/6(n+1)(2n+1),该结论在P_(119),例1中用数学归纳法给以证明,P_(124)练习题中用数学归纳法证明:1·2+2·3+3·4+…n(n+1)=(1/3)n(n+ 1)(n+2),P_(124)习题二十三又用数学归纳法证明1~3+2~3+3~3+…+n~3=(1/4)n~2(n+1)~2;1~2+3~2+5~2+…+(2n-1)~2=(1/3)n(4n~2-1),P_(132)复习参考六用数学归纳法证明:1×2×3+2×3×4+3×4×5+…+n(n+1)(n+2)=(1/4)n(n+1)(n+2)(n+3),诸如此类的有关自然数数列求和都是给出了结论,然后用数学归纳法进行证明,不少同学会提出它们作为书皮封面说明是很重要的,那么其结论是怎么来得呢?这是有关自然数数列求和一类公式性的结论,在高考中也曾出现过.例:89年理科第23题是否存在常数a、b、c使得等式:1×2~2+2×3~2+…+n(n+1)~2=(1/12)n(n+1)(an~2+bn+c),对于一切自然数都成立,并证明你的结论.以上所举自然数数列是一类相关习题,下面给出它们结论的证明.(1)1×2+2×3+3×4+n(n+1)=(1/3)n(n+1)(n+2)(2)1×2×3+2×3×4+…+n(n+1)(n+2)=(1/4)n(n+1)(n+2)(n+3)证1:设S=1×2×3+2×3×4+…+n(n+1)(n+2)利用课本错位减法S=1×2×3+2×3×4+3×4×5+…+n(n+1)(n+2)-S=-〔1×2×3+2×3×4+…(n-1)n(n+1)+n (n+1)(n+2)〕0=3×1×2  相似文献   

2.
在中学数学中 ,经常遇到分子的次数大于或等于分母次数的分式 ,如1 - 3xx + 2 、x2 + 7x + 1 0x + 1等 .在实际应用中 ,可以把它们化成类似于代分数的形式 ,即整式部分 +分式部分 (分子次数小于分母次数 ) ,我们就把这种形式的分式叫做分部分式 ,下面举例说明其在函数教学中的应用 .例 1 作出函数 y =3- 2xx - 3的图象 .分析 函数 y =3- 2xx - 3不属于中学数学中的任何一类初等函数 ,除用描点法外 ,无法直接作出其图象 ,但如果利用分部分式 ,则可由图象变换得到该函数的图象 ,由 y =3- 2xx - 3,得y =- 3x - 3- 2 .先作出 …  相似文献   

3.
硅的重要化合物——硅酸是高中化学新课标关于常见无机物及其应用中要求通过实验了解的基本内容之一[1]。现行普通高中教科书《化学1·必修》(人教版)在介绍硅酸的有关知识时,所安排的实验是[2]:在试管中加入3~5mL Na2SiO3溶液(饱和Na2SiO3溶液按1:2或1:3的体积比用水稀释),滴入1~2滴酚酞溶液,再用胶头滴管逐滴加入稀盐酸,边加边振荡,至溶液红色变浅并接近消失时停止。  相似文献   

4.
求值题灵活多变,不容易掌握其规律,下面对一道求值题作些变化,仅供参考 例已知了x 3y 42 了3x 11y 152一。,求xZ 2y2一422,。,去二一产令汽井子的值。xz y‘ 222一’一“ 解:,.’了x 3y 4: 丫3x 11y 152一。x 3y 42=03x 1 ly 152=O乡·原式- 2又(一粤:):一422 乙1尹 1、。‘,3卜万z,“十气一下万z)“十22“ 乙乙; 当z一。时,无意义 引导学生讨论: 1.若改变已知条件,使结果不变,则有如下几种情形: (1)(x 3y 42)竺 (3x 1 ly 1 52)2=(); (2)一x 3y 421 一3x 1 ly 1 52一(); (3)了x 3y 42 (3x 1 ly 152)2=o; (4)丫x 3y 42 1 3x 1 ly 1521=o; (5…  相似文献   

5.
1 仪器装置图(如图 1所示 )2 仪器特点及用途2 1 特点本教具用废旧材料制成 ,使气体反冲的教学形象化 ,实验现象更为科学生动。2 2 用途( 1 )气体的反冲现象实验。( 2 )水的沸腾现象实验。3 制作材料本教具的结构分三部分。( 1 )带转轴的锅炉 :1 5mm铁珠 1个 ,4mm长1 2 0mm铁丝 1条 ,做成转轴 ;4mm玻璃管 1支。带铝帽的玻璃药瓶 3个。( 2 )酒精灯 :灯帽 ,废旧彩笔笔帽 ,灯管及灯芯。4mm长 4 0mm金属管 3支 ,带铝帽的药瓶 3个。( 3 )支座 :废喇叭上的环形磁铁 1个 ,坏塑料桶铁丝提梁 1个 ,1 65mm圆木做成蘑菇…  相似文献   

6.
在连续多步反应的计算中,如果依据反应的过程采用逐步分析,逐步计算,过程较繁琐。这里我们以例题为例介绍一种巧解涉及多步反应的计算的方法———待定系数法。待定系数法不仅可以用来判断和计算产物,还可以用来讨论所加试剂的量的范围。例一:在1L0.1mol.L-的AlCl3溶液中加入2mol.L-的NaOH溶液,当产生3.9克沉淀时,求加入的NaOH溶液的体积。分析,第一步反应:AlCL3 3NaOH=Al(OH)3↓ 3NaCl(1)第二步反应:Al(OH)3 NaOH=NaAlO2 2H2O设:第二步反应消耗的Al(OH)3的物质的量为xmol则有xAl(OH)3 xNaOH=xNaAlO2 2xH2O(2)(1) (2)得(3):AlCL3 (3 x)NaOH=(1-x)Al(OH)3↓ xNaAlO2 3NaCl 2xH2O(3),我们可以根据(3)式进行分析、判断和计算。0≤x≤1。当x=0时:即只生成Al(OH)3无NaAlO2生成。当x=1时:即有NaAlO2生成。当0  相似文献   

7.
《实验教学与仪器》(长沙)2007年6期34页上,有“用CaCl2溶液区分NaHCO3和Na2CO3溶液”为题的一篇文章。我的基本观点认为,用CaCl2溶液作为NaHCO3和Na2CO3的区分试剂的方法欠妥。1Na2CO3和NaHCO3的一般鉴别方法(1)如果两种试样都是固体——用加热法量多(如有数克或更多)能受热分  相似文献   

8.
目的:测试核心力量训练过程中排球运动员核心稳定性、跳发球速度和成功率的变化,探讨核心力量提升跳发球速度和成功率的训练机制.方法:以36名不同等级排球运动员为被试,每周训练3次,训练前(H0)、4周末(H1)、8周末(H2)、12周末(H3)和16周末(H4)对运动员侧桥、侧抛实心球和1min仰卧起坐及跳发球速度和成功率各测量1次.结果:运动员核心稳定性较训练前显著提高,左右侧桥时间和1min仰卧起坐次数提升幅度在H2-H1、H3-H2和H4-H3具有显著差异,侧抛实心球距离则在H4-H3有提升但无显著差异,且在H3-H2均随运动等级的提高,提升幅度越明显;运动员跳发球质量较训练前显著提高,跳发球速度提升幅度在H2-H1和H3-H2具有显著差异,成功率提升幅度在H2-H1、H3-H2和H4-H3具有显著差异,且在H3-H2都随运动等级提高,提升幅度逐渐减弱.结论:水平面核心肌群的稳定性可能是影响跳发球速度的关键,核心力量训练影响跳发球速度和成功率的机制可能是通过人体不同水平面核心稳定性的联合作用来完成的.  相似文献   

9.
反证法是间接证法的一种。如果我们把欲证的命题写成“若 A则 B( A→ B)”的形式 ,则反证法就是从需证命题结论 B的相反结论 B出发 ,通过正确的逻辑推理导出矛盾 ,推翻 B,从而断定待证结论 B成立。反证法有下面几种逻辑形式 :1.A→ B B→ A.证明 :A→ B A∨ B B∨ A B∨ A B→ A.例 1.已知 p3 +q3 =2 求证 p +q 2 .证明 :假设 p +q >2则 p3 >( 2 -q) 3 =8-12 q +6q2 -q3  p3 +q3 >2 ( 4 -6q +3 q2 )所以 p3 +q3 ≠ 2如若不然 ,有 2 ( 4 -6q +3 q2 ) <2  3 ( q2 -2 q +1) <0 .  ( q -1) 2 <0 .矛盾故 p +q 2 .2 .A…  相似文献   

10.
设 p是奇素数,证明了:当 p=12r2 1,其中 r是正整数,则方程 x3 1=3py2无正整数解 (x,y).  相似文献   

11.
The thesis mainly discusses the character of the heroine in Charlotte Brontes famous novel "Jane Eyre". There are three major parts-introduction,analysis which is the main body of the thesis,and conclusion.Jane Eyre,the heroine,is a new woman image who requires independence equality and freedom.The thesis just analyzes Janes these rebellious characters through four peroods of her experiences.First,in her childhood,she has shown her rebellious spirit.As an orphan,Jane suffers a lot of misery.Not only her aunt treats her cruelly,her cousins despise her,but also do servants have a prejudice against her.In Janes immature heart, she is unwilling to bear ill treatment.She rebels them bravely.Second,when she studies at Lowood,her rebellious spirit is exposed furtherly.Her view doest stay in Mrs Reeds,instead turns to the whole society.She makes hypocrisy of so-called charity to be discovered completely.At the same time,she declares her independent,equal rebellious thought to her friend-Helldn who endures oppression willingly.Third,she,as a governess in Thornfield Hall falls in love with Rochester-her master.During this period,her thought grows into maturity.Thought she loves him passionately,she never loses her dignity and independence for him.When she knows his mad wife still lives,she makes up her mind to leave him.For she doesnt want to become his mistress.Fourth,her refusal of St Johns proposal of marriage depicts Janes character.She knows John does not love her at all and his purpose of marriage is only to perform his great task missionary.Jane does want to become a sacrifice.She breaks traditional morality,then she goes back to Rochester.  相似文献   

12.
"Midnight"is a poem written by Archibald·Lampman,a Canadian poet,who loved nature very much,but his poor health prevents him from being very active in the outdoor life.So he is often the quite,thoughtful observer of nature in his poems.This article mainly talks about how to appreciate the poem in the following aspects:word selecting,rhyme,sentence structure and atmosphere.After reading this poem,we cannot get rid of the air of horror and mystery."Midnight" reveals another aspect of the nature:wild,rough and unknown.There is something else in the nature that can awe human beings even though we don't know what it is.  相似文献   

13.
The context of a word consists of the other words surrounding it and the situation in which it is used.When we come across a new word in our reading,instead of looking it up in a dictionary for its definition,we can guess its meaning from its context.  相似文献   

14.
Since the late 1960s,culture has been considered tighter with communication.Culture IS based on the community of communication.Communication involves people and their environment.Thus culture is an important factor in communication.Today with modem economic and technological development,intercultural communication is mole important than ever before. When people from different cultural background communicate with each other,their social stereotype pattern of behavior, their habits of language and thought differ from one another,because these are the possible factors that affect intercultural communications.Culture norms also change,culture may be transferred as signs but we have to study and understand the above carefially.  相似文献   

15.
Introduction Whatisculture?Toputitsimply,culturemeansthe totalwayoflifeofaperson.Thissimpledefinitionimplies thatculturereferstothepattersofcustoms,traditions,socialhabits,values,beliefsandlanguageofasociety.As cultureissoinclusive,itincludesvirtuallyeverythingthat agroupofpeoplethink,say,doandmake.Followingthedefinitionofsociologists,theterm culturereferstothetotalpatternofbeliefs,customs,institutions,objects,andcharacterizesthelifeofhuman community.“Cultureconsistsofallthesharedproductsof …  相似文献   

16.
The article introduces Shakespeare's tragedy "Hamlet".Hamlet wants to revenge for his father.But when the opportunity is coming,he delays his revenge.The passage analyzes the causes of his delay from Hamlet's characters.  相似文献   

17.
Chapter Ⅰ Introduction Sitting in the rocking chair,Carrie dreams her future.This is the deep impression the novel"Sister Carrie"gives us,which is written by Theodore Dreiser(1871-1945),the great American realism writer.  相似文献   

18.
当代中国武术经历了时代的沧桑和变迁,在历经了文化和历史的发展与洗礼之后,依然发展、繁衍至今。在这样一个漫长的过程中,伴随着以社会环境和社会人群价值取向为主的变迁与变化,当代中国武术的发展与当代社会的发展正逐渐的呈现出某些相背离和不和谐的表象。通过研究,我们发觉中国武术中原本一些内在的东西正在不断的被遗忘,正在不断的流逝。本文试从中国武术在当代发展中的问题境域入手,解读中国武术在当今世界和社会中存在的一些问题,希望能够从中找到中国武术发展的"合法性"或"合时性"的内在依据,以挺立中国武术的脊梁。  相似文献   

19.
论凯恩斯和他的内需理论   总被引:1,自引:0,他引:1  
社会实践是检验真理的唯一标准。诚然 ,真理的认同是社会实践的依据。在世界经济发展史上 ,西方著名的经济学家数以百计。然而 ,凯恩斯“通论”中的内需理论一直是当今世界经济学家们研究宏观经济理论的重要组成部分 ,也是企业改革 ,发展市场经济 ,扩大就业的强大动力  相似文献   

20.
国外锻炼行为理论研究综述   总被引:24,自引:2,他引:22  
正确认识和促进与健康有关的锻炼行为必须以合理的理论为基础。对国外锻炼心理学领域与健康有关的锻炼行为理论和模型:健康信念模型、保护动机模型、合理行为模型、计划行为模型、自我决定模型、社会认知模型、自我效能模型和跨理论模型进行分析,评价其成功和不足的地方。在前人研究的基础上提出态度-行为综合模型作为研究锻炼行为参与新的研究方向。  相似文献   

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