高三数学第一轮复习-等差数列.pptVIP

高三数学第一轮复习 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 学习目标 1、理解等差数列的概念、通项公式、等差中项公式，会用公式解决问题 2、掌握等差数列的前n项和公式，体会等差数列的通项及等差数列的前n项和可分别表示为一次函数和二次函数 3、探索并总结等差数列的性质，会运用性质解决有关问题 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 学习活动1：梳理基础知识 1.等差数列的定义: 若数列从第二项起，每一项与它的前一项的差是同一个常数，则数列是等差数列。其中常数是公差 2.通项公式: 通项公式推广: Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 3.等差中项: 若a，b，c成等差数列，则b称a与c的 等差中项. 4.等差数列前n项和公式: 学习活动1：梳理基础知识 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 5.等差数列的判定方法: ?定义法: ?中项公式法: ?通项公式法: 学习活动1：梳理基础知识 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 性质 等差数列{an}常用的性质 性质1 性质2 性质3 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 题型?:关于基本量的问题 例1:在等差数列{an}中， （1）已知a15=33，a45=153，求a61； （2）已知S8=48，S12=168，求a1和d； （3）已知a6=10，S5=5，求a8和S8； （4）已知a16=3，求S31； 学习活动1：亲身体验 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例题讲解 题型2:等差数列前n项和的应用 例2:数列{an}中，Sn=100n-n2(n?N+) （1）{an}是什么数列? （2）若bn=|an|，求{bn}的前n项和 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例题讲解 题型3:等差数列的证明 例3:设{an}是等差数列， 求证:{bn}是等差数列 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 练习巩固 1.已知等差数列{an}中,a7+a9=16,a4=1,则a12=( ) A.15 B.30 C.31 D.64 2.首项为-24的等差数列,从第10项起为正,则公差d的取值范围是( ) A. B. C. D. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 4.等差数列{an}中,a1= ,a2+a5=4,an=33,则n=( ) 练习巩固 3.等差数列{an}中,a2=-6,a8=6,Sn是{an