BC Calculus: Radius of Convergence for Power Series, Exams of Calculus

Various tests to determine the convergence or divergence of power series in BC Calculus, including the Nth-Term Test, Direct Comparison Test, and Ratio Test. It also discusses the definitions of absolute and conditional convergence and the Convergence Theorem for Power Series. The document concludes by finding the radius and interval of convergence for several power series.

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BC Calculus
10.4 Radius of Convergence
Convergence for a :
Geometric Series: Maclaurin series for :, , esin x cos x x
Nth-Term Test for Divergence
Recall from 10.1 infinite series:
The nth-term Test for Divergence
If then diverges. *The converse of this ๎ฌžis not ๎ฌžtrue. If the= ,lim
nโ†’โˆž an/ 0 โˆ‘
โˆž
n=1
anlim
nโ†’โˆž an= 0
series ๎ฌžcould๎ฌž converge.
1. Determine if the series diverges:
a. โˆ‘
โˆž
n=0
2n
b. โˆ‘
โˆž
n=1
n!
2n!+1
c. โˆ‘
โˆž
n=1 n
1
pf3
pf4
pf5

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Download BC Calculus: Radius of Convergence for Power Series and more Exams Calculus in PDF only on Docsity!

10.4 Radius of Convergence

Convergence for a :

Geometric Series: Maclaurin series for sin x , cos x , ex :

Nth-Term Test for Divergence

Recall from 10.1 infinite series:

The nth-term Test for Divergence If (^) n limโ†’โˆž an =/ 0 , then โˆ‘ diverges. *The converse of this is not true. If the

โˆž n =

an (^) n limโ†’โˆž an = 0 series could converge.

  1. Determine if the series diverges: a. โˆ‘

โˆž n =

2 n^ b. โˆ‘

โˆž n =

n! 2 n !+1 c.^ โˆ‘

โˆž n =1 n

1

10.4 Radius of Convergence

Direct Comparison Test

The direct comparison test is a tool that we can use to determine convergence for complicated, positive series by comparing them with simpler series.

Direct Comparison Test Let 0 < an < bn for all n

  1. If โˆ‘ converges, then converges

โˆž n =

bn โˆ‘

โˆž n =

an

  1. If โˆ‘ diverges, then diverges.

โˆž n =

an โˆ‘

โˆž n =

bn

  1. Determine convergence or divergence. a. โˆ‘

โˆž n =

1 2+3 n^ b.^ โˆ‘

โˆž n =

x^2 n ( n !)^2 c.^ โˆ‘

โˆž n =

x^2 n n !+

10.4 Radius of Convergence

Ratio Test

Ratio test Let โˆ‘ an be a series with nonzero terms.

  1. โˆ‘ an converges absolutely if n limโ†’โˆž^ ||^ aann +1^ || < 1
  2. โˆ‘ an diverges if n limโ†’โˆž^ ||^ aann +1^ || > 1
  3. The ratio test is inconclusive if (^) n limโ†’โˆž^ ||^ aann +1^ || = 1

The ratio test is particularly useful for series that converge rapidly (i.e. factorials or exponentials).

  1. Determine Convergence or Divergence: a. โˆ‘

โˆž n =0 n!

2 n b. โˆ‘^ โˆž n =0 3

n^2 2 n n +

10.4 Radius of Convergence

c. โˆ‘

โˆž n =1 n!

nn

d. โˆ‘(โˆ’ )

โˆž n =

1 n^ n โˆš+1 n

10.4 Radius of Convergence

c. โˆ‘

โˆž n =0 n^^2

(โˆ’1) ( nx โˆ’2) n +1 n d. โˆ‘

โˆž n =

( x โˆ’3) n + ( n +1) 4 n +