This document defines and explains several types of infinite series and tests used to determine if they converge or diverge. It introduces infinite series and sequences of partial sums. It then discusses tests for convergence/divergence including the geometric series test, limit comparison test, ratio test, root test, alternating series test, absolute convergence test, and radius of convergence for power series. Types of series covered include Taylor series and Maclaurin series expansions.
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Ktu - s1 me module 1 (Calculus Module 1)
1. Infinite Series
1 + 2 + 3 +
=1
Sequence of Partial Sums
1 = 1
2 = 1 + 2
3 = 1 + 2 + 3
..
= 1 + 2 + + etc.
1 if the sequence of partial sums ( ) converges
then the series
=1 converges
2 lim is the sum of the series
Geometric Series
=1
= + + 2
+ , ( 0)
1 Converges if || < 1
2 Diverges if || 1
Necessary condition for convergence
基 $
=1
≠ lim
= 0
lim
0 ≠ ≠
P Test
lim
1
p > 1, p 1
Comparison Test
If and If are two positive term series
then if , then
a) If is convergent then is also
convergent
b) If is divergent then is also divergent
Limit form of comparison test:
lim
= 0 is a non-zero number.
Then & converges or diverges together.
DAlemberts Ratio Test
If is a positive term series such that
lim
+1
= then the series
a) Converges if < 1
b) Diverges if > 1
c) Test fails if = 1
Root Test
If is a positive term series such that
lim ( )
1
= then the series
a) Converges if < 1
b) Diverges if > 1
c) Test fails if = 1
Alternating series
A series whose terms are alternatively positive
and negative
Leibnitz Test
If the alternating series 1 2 + 3 is such
that
a) +1 , and
b) lim = 0
Then the series converges
Absolute convergence
A series
=1 is called absolutely
convergent if | |
=1 is convergent.
If
=1 is convergent and | |
=1 is
divergent we call the series conditionally convergent.
Taylors Series
The Taylors Series expansion of () about
= is
() = () +
1!
() +
( )2
2!
霞()
+
( )3
3!
霞霞() + ..
Maclaurins Series
Put = 0 in Taylors series
() = (0) + ヰ(0) +
2
2!
"(0) +
3
3!
霞霞(0) + .
Radius of Convergence
If
=1 is a power series which
converges absolutely for || < and those absolute
term diverges for || > and || = if either
converges or diverges absolutely. Then R is knowns
as the Radius of convergence of the power series.