partial sums and infinite series - Miss Sahady PSHS Class...

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook 1 March 06, 2014 Nov 186:33 PM Warm-Up: 1. 2. Given the sequence 4,8,16,32,..., answer the following questions. What are the next 3 terms in the sequence? What is the common ratio? What is the 15 th term in the sequence? What term number is equal to 512? 3. 4. Nov 186:28 PM partial sums and infinite series Ch. 12 level 2

Transcript of partial sums and infinite series - Miss Sahady PSHS Class...

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Nov 18­6:33 PM

Warm-Up:

1.

2.

Given the sequence 4,8,16,32,..., answer the following questions.

What are the next 3 terms in the sequence?

What is the common ratio?

What is the 15th term in the sequence?

What term number is equal to 512?

3.4.

Nov 18­6:28 PM

partial sums and infinite 

seriesCh. 12 level 2 

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Nov 18­6:31 PM

Target

Agenda

Purpose

Evaluation

Agenda

Purpose

Evaluation

TSWBAT: define an arithmetic and geometric partial and infinite sums

Warm-Up/Homework Check

Lesson

BAT: Extend knowledge of patterns and coming to conclusion about them. Prep for summations and Calculus and Statistics. And understand mathematical induction.

Some exercises

Nov 18­6:42 PM

Partial Sumscreate a sequence that adds the prior terms together up until the term at that number

s1=     

s2= 

s3= 

s4 =  sn= 

1st partial sum

2nd partial sum

 3rdpartial sum

4th partial sum

nth partial sum 

a1

What is the 75th term?

a1 + a2

a1 + a2 + a3a1 + a2 + a3 + a4

a1 + a2 + a3 + a4 + ...+an 

... ...

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Nov 18­6:42 PM

Sequences of Partial Sums:an = 1/2n    

s1=     

s2= 

s3= 

s4 =  sn= 

Jan 30­3:33 PM

ex.    ak= k2 

S4=

ex.    ak= k 

S6=

ex.    ak= 1/(kx) 

S100=

ex.    ak= 2 

S30=

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Jan 30­3:46 PM

Writing the sum....figuring out the sequence

14 + 24 + 34 + 44 + 54 + 64 + 74 ex.

ex. √1 + √2 + √3 + √4 + √5 + ... + √76

Nov 18­6:28 PM

arithmetic series

Ch. 12 level 2 

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

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The sum of an arithmetic sequence equals...! 

Sn= a + (a+d) + (a+2d) +...+ [a+(n­1)d] 

=   n  2(a + an)

2a + ann )(or

Jan 30­3:39 PM

If the sequence is:

Find the sum of the first 40 terms

3, 7, 11, 15...

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Jan 30­3:46 PM

If the sequence is all odd numbers and an=81, find the series.

Mar 6­4:56 PM

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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Jan 30­5:02 PM

example. Triangle problems

level Total

How many squares will make up the triangle if there are 50 levels?

Nov 18­6:28 PM

geometric series

Ch. 12 level 2 

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Feb 4­7:45 AM

The formula for the sum of a geometric sequence

Feb 4­7:51 AM

Example: given the nth term and geometric partial sum

find the 4th partial sum, S4,

if a= 7, r = ­2/3, and n=4

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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Infinite SeriesTheoretically: its like eating cake, if you always only eat half of what is left, there is always some left.  The total you eat never exceeds the whole cake or 1....

1/2 + 1/4 + 1/8 + 1/16 +...+ (1/2)n

Ʃ (1/2)n = 1­ (1/2)k 

Sn => 1 as n=> ∞ 

because as 2k gets really big, 1/2k will have a big denominator, making a smaller and smaller fraction off to subtracting 0

the for

mula!

IF Sn GETS CLOSE TO A FINITE NUMBER S, AS n GETS LARGE, THEN S IS THE SUM OF THE INFINITE SERIES:

IN THIS CASE, S = 1

1=Ʃ (1/2)n

n=1

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Nov 18­6:42 PM

Sum of an Inifinite Geometric Series

if |r|<1 (r is a fraction less than 1

a + ar+ ar2 + ar3 + ...+ arn­1 + ...

Ʃ arn  =  a1­ rn=1

Nov 18­6:42 PM

Examples

ex. if a = 2 r = 1/5, what is the infinite sum?  

its a straight line!

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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Evaluation:

Practice!  pg. Level 2 worksheet

1.

2.

if the sequence is 2,8,14,20... what is S20?

What is S100 of the geometric sequence:

a= 1, r = 1/2

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Level 2 Arithmetic and Geometric Partial and Infinite Sums.notebook

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March 06, 2014

Feb 5­7:30 AM