系列

本文主要学习系列的基本概念分类。主要包括几何级数、二项式系数、调和级数。通过举例说明几何级数的和是什么。通过另一个例子幂级数和利用二项式定理等来学习讨论系列的运用。
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1.Series Geometric Series Binomial Coefficients Harmonic Series

2.Sum of a Geometric Series What is Method 1: Prove by induction that for every n≥0, And then make some argument about the limit as n →∞ to conclude that the sum is 2.

3.Sum of a Geometric Series Another way. Recall that and plug in x = ½ ! These “formal power series” have many uses.

4.Another example What is Since

5.Another Example What is Generalize. Note that S=F(1/3) where

6.Manipulating Power Series

7.Another Approach But then

8.Identities involving “Choose” What is “Set Theory” derivation Let S be a set of size n This is the sum of the number of 0 element subsets, plus the number of 1-element subsets, plus …, plus the number of n -element subsets Total 2 n

9.Binomial Theorem because if you multiply out ( x+y)(x+y)(x+y )…( x+y ) the coefficient of x i y n-i is the number of different ways of choosing x from i factors and y from n-i factors

10.Using the Binomial Theorem Since substituting x = y =1 yields

11.Using the Binomial Theorem What is Try to make this look like the binomial thm

12.Stacking books Can you stack identical books so the top one is completely off the table? 4/12/12

13.Stacking books Can you stack identical books so the top one is completely off the table? One book: balance at middle 4/12/12 1 1

14.Stacking books Two books: balance top one at the middle, the second over the table edge at the center of gravity of the pair 4/12/12 1 1 1 ½

15.Stacking books Three books: balance top one at the middle, the second over the third at ½, and the trio over the table edge at the center of gravity 4/12/12 1 ½

16.Stacking books Three books: balance top one at the middle, the second over the third at ½, and the trio over the table edge at the center of gravity = (1+2+2½)/3 = 1⅚ from right end 4/12/12 1 ½ 1⅚

17.Stacking books Three books: balance top one at the middle, the second over the third at ½, and the trio over the table edge at the center of gravity = (1+2+2½)/3 = 1⅚ from right end 4/12/12 1 ½ ⅓ 1⅚ See a pattern?

18.The Harmonic Series Diverges Let . Then for any n, Doubling the number of terms adds at least ½ to the sum Corollary. The series diverges, that is, 4/12/12

19.Proof by WOP that the Harmonic Series Diverges 4/12/12

20.The Harmonic Series Diverges 4/12/12

21.So w ith a stack of 31 books you get 2 book lengths off the table! And there is no limit to how far the stack can extend ! 4/12/12 http://mathforum.org/advanced/robertd/harmonic.html

22.FINIS