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(a) an ordered list of objects.
12. 1 A sequence is… (a) an ordered list of objects. (b) A function whose domain is a set of integers. Domain: 1, 2, 3, 4, …,n… Range a1, a2, a3, a4, … an… {(1, 1), (2, ½), (3, ¼), (4, 1/8) ….}
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Describe a pattern for each sequence. Write a formula for the nth term
Finding patterns Describe a pattern for each sequence. Write a formula for the nth term
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Write the first 5 terms for
On a number line As a function The terms in this sequence get closer and closer to 1. The sequence CONVERGES to 1.
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The terms in this sequence do not get close to
Write the first 5 terms The terms in this sequence do not get close to Any single value. The sequence Diverges
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The sequence converges to 3.
Write the terms for an = 3 The terms are 3, 3, 3, …3 The sequence converges to 3.
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y= L is a horizontal asymptote when sequence converges to L.
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A sequence that diverges
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Write the first 5 terms of the sequence.
Sequences Write the first 5 terms of the sequence. Does the sequence converge? If so, find the value. The sequence converges to 0. The sequence diverges.
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Represents the sum of the terms in a sequence.
12.2 Infinite Series Represents the sum of the terms in a sequence. We want to know if the series converges to a single value i.e. there is a finite sum. The series diverges because sn = n. Note that the Sequence {1} converges.
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If the sequence of partial sums converges, the series converges
Partial sums of and If the sequence of partial sums converges, the series converges Converges to 1 so series converges.
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Can use partial fractions to rewrite
Finding sums Can use partial fractions to rewrite
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The partial sums of the series
. Limit
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Find r (the common ratio)
Geometric Series Each term is obtained from the preceding number by multiplying by the same number r. Find r (the common ratio)
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Write using series notation
Is a Geometric Series Where a = first term and r=common ratio Write using series notation
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The sum of a geometric series
Sum of n terms Multiply each term by r subtract Geometric series converges to If r>1 the geometric series diverges.
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Find the sum of a Geometric Series
Where a = first term and r=common ratio The series diverges.
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Repeating decimals-Geometric Series
The repeating decimal is equivalent to 8/99.
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Series known to converge or diverge
1. A geometric series with | r | <1 converges 2. A repeating decimal converges 3. Telescoping series converge A necessary condition for convergence: Limit as n goes to infinity for nth term in sequence is 0. nth term test for divergence: If the limit as n goes to infinity for the nth term is not 0, the series DIVERGES!
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Convergence or Divergence?
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A monotonic sequence that is bounded Is convergent.
A sequence in which each term is less than or equal to the one before it is called a monotonic non-increasing sequence. If each term is greater than or equal to the one before it, it is called monotonic non-decreasing. A monotonic sequence that is bounded Is convergent. A series of non-negative terms converges If its partial sums are bounded from above.
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12. 3 The Integral Test Let {an} be a sequence of positive terms. Suppose that an = f(n) where f is a continuous positive, decreasing function of x for all xN. Then the series and the corresponding integral shown both converge of both diverge. f(n) f(x)
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The series and the integral both converge or both diverge
Area in rectangle corresponds to term in sequence Exact area under curve is between If area under curve is finite, so is area in rectangles If area under curve is infinite, so is area in rectangles
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Using the Integral test
The improper integral diverges Thus the series diverges
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Using the Integral test
The improper integral converges Thus the series converges
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Harmonic series and p-series
Is called a p-series A p-series converges if p > 1 and diverges If p < 1 or p = 1. Is called the harmonic series and it diverges since p =1.
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Identify which series converge and which diverge.
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12. 4Direct Comparison test
be a series with no negative terms Let Converges if there is a series Where the terms of an are less than or equal to the terms of cn for all n>N. Diverges if there is a series Where the terms of an are greater than or equal to the terms of dn for all n>N.
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Limit Comparison test and and Amd and Diverges. Limit Comparison test
Then the following series both converge or both diverge: and Converges then Converges. Amd and Diverges. Diverges then
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Convergence or divergence?
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A series in which terms alternate in sign
Alternating Series A series in which terms alternate in sign or
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Alternating Series Test
Converges if: an is always positive an an+1 for all n N for some integer N. an0 If any one of the conditions is not met, the Series diverges.
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Absolute and Conditional Convergence
A series is absolutely convergent if the corresponding series of absolute values converges. A series that converges but does not converge absolutely, converges conditionally. Every absolutely convergent series converges. (Converse is false!!!)
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Is the given series convergent or divergent
Is the given series convergent or divergent? If it is convergent, its it absolutely convergent or conditionally convergent?
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This is not an alternating series, but since
a) Is the given series convergent or divergent? If it is convergent, its it absolutely convergent or conditionally convergent? This is not an alternating series, but since Is a convergent geometric series, then the given Series is absolutely convergent.
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Converges by the Alternating series test.
b) Is the given series convergent or divergent? If it is convergent, its it absolutely convergent or conditionally convergent? Converges by the Alternating series test. Diverges with direct comparison with the harmonic Series. The given series is conditionally convergent.
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By the nth term test for divergence, the series Diverges.
c) Is the given series convergent or divergent? If it is convergent, its it absolutely convergent or conditionally convergent? By the nth term test for divergence, the series Diverges.
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Converges by the alternating series test.
d) Is the given series convergent or divergent? If it is convergent, its it absolutely convergent or conditionally convergent? Converges by the alternating series test. Diverges since it is a p-series with p <1. The Given series is conditionally convergent.
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Let be a series with positive terms and
The Ratio Test Let be a series with positive terms and Then The series converges if ρ < 1 The series diverges if ρ > 1 The test is inconclusive if ρ = 1.
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Let be a series with non-zero terms and
The Root Test Let be a series with non-zero terms and Then The series converges if L< 1 The series diverges if L > 1 or is infinite The test is inconclusive if L= 1.
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Convergence or divergence?
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Procedure for determining Convergence
. Procedure for determining Convergence
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Power Series (infinite polynomial in x)
Is a power series centered at x = 0. and Is a power series centered at x = a.
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Examples of Power Series
Is a power series centered at x = 0. and Is a power series centered at x = -1.
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Geometric Power Series
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The graph of f(x) = 1/(1-x) and four of its polynomial approximations
. The graph of f(x) = 1/(1-x) and four of its polynomial approximations
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Convergence of a Power Series
There are three possibilities 1)There is a positive number R such that the series diverges for |x-a|>R but converges for |x-a|<R. The series may or may not converge at the endpoints, x = a - R and x = a + R. 2)The series converges for every x. (R = .) 3)The series converges at x = a and diverges elsewhere. (R = 0)
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What is the interval of convergence?
Since r = x, the series converges |x| <1, or -1 < x < 1. In interval notation (-1,1). Test endpoints of –1 and 1. Series diverges Series diverges
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Geometric Power Series
Find the function Find the radius of convergence
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Geometric Power Series
Find the radius of convergence Find the interval of convergence For x = -2, Geometric series with r < 1, converges For x = 4 By nth term test, the series diverges. Interval of convergence
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Finding interval of convergence
Use the ratio test: R=1 (-1, 1) For x = 1 For x = -1 Interval of convergence [-1, 1) Harmonic series diverges Alternating Harmonic series converges
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Differentiation and Integration of Power Series
If the function is given by the series Has a radius of convergence R>0, the on the interval (c-R, c+R) the function is continuous, Differentiable and integrable where: The radius of convergence is the same but the interval of convergence may differ at the endpoints.
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Constructing Power Series
If a power series exists has a radius of convergence = R It can be differentiated So the nth derivative is
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Finding the coefficients for a Power Series
All derivatives for f(x) must equal the series Derivatives at x = a.
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If f has a series representation centered at x=a, the series must be
If f has a series representation centered at x=0, the series must be
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Form a Taylor Polynomial of order 3 for sin x at a =
f(n)(x) f(n)(a) f(n)(a)/n! sin x 1 cos x 2 -sin x 3 -cos x
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The graph of f(x) = ex and its Taylor polynomials
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Find the derivative and the integral
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Taylor polynomials for f(x) = cos (x)
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Converges only at x = 0
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