Calculus 2 : Types of Series

Study concepts, example questions & explanations for Calculus 2

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Example Questions

Example Question #2 : Limits Of Sequences

Calculate the sum of the following infinite geometric series:

Possible Answers:

Correct answer:

Explanation:

This is an infinite geometric series.

The sum of an infinite geometric series can be calculated with the following formula,

 , where  is the first value of the summation, and r is the common ratio.

Solution:

Value of  can be found by setting 

r is the value contained in the exponent

 

 

Example Question #26 : Arithmetic And Geometric Series

Calculate the sum of the following infinite geometric series:

Possible Answers:

Correct answer:

Explanation:

This is an infinite geometric series.

The sum of an infinite geometric series can be calculated with the following formula,

 , where  is the first value of the summation, and r is the common ratio.

Solution:

Value of  can be found by setting 

r is the value contained in the exponent

Example Question #21 : Arithmetic And Geometric Series

Calculate the sum of the following infinite geometric series:

Possible Answers:

Correct answer:

Explanation:

This is an infinite geometric series.

The sum of an infinite geometric series can be calculated with the following formula,

 , where  is the first value of the summation, and r is the common ratio.

Solution:

Value of  can be found by setting 

r is the value contained in the exponent

Example Question #31 : Types Of Series

Evaluate:

Possible Answers:

The series does not converge.

Correct answer:

Explanation:

The method of partial fractions can be used to rewrite this expression:

 

The solution can easily be found to be , and the series can then be rewritten:

The series is telescoping and is equal to the following:

 

 

Example Question #211 : Series In Calculus

Evaluate:

Possible Answers:

Correct answer:

Explanation:

The method of partial fractions can be used to rewrite this expression:

 

The solution can easily be found to be , and the series can be rewritten:

This is a telescoping series:

Example Question #1 : Harmonic Series

The Harmonic series is a special case of a -series, with  equal to what?

Possible Answers:

Correct answer:

Explanation:

-series is a series of the form , and the Harmonic Series is . Hence .

Example Question #1 : Harmonic Series

Which of the following tests will help determine whether   is convergent or divergent, and why?

Possible Answers:

Root Test: Since the limit as  approaches to infinity is zero, the series is convergent.

Integral Test: The improper integral determines that the harmonic series diverge.

Divergence Test: Since limit of the series approaches zero, the series must converge.

Nth Term Test: The series diverge because the limit as  goes to infinity is zero.

P-Series Test: The summation converges since .

Correct answer:

Integral Test: The improper integral determines that the harmonic series diverge.

Explanation:

The series  is a harmonic series.  

The Nth term test and the Divergent test may not be used to determine whether this series converges, since this is a special case.  The root test also does not apply in this scenario.

According the the P-series Test,  must converge only if .  Therefore this could be a valid test, but a wrong definition as the answer choice since the series diverge for .

This leaves us with the Integral Test.

Since the improper integral diverges, so does the series.

 

Example Question #3 : Harmonic Series

Determine whether the following series converges or diverges:

Possible Answers:

The series may (absolutely) converge, diverge, or conditionally converge

The series conditionally converges

The series (absolutely) converges

The series diverges

Correct answer:

The series (absolutely) converges

Explanation:

Given just the harmonic series, we would state that the series diverges. However, we are given the alternating harmonic series. To determine whether this series will converge or diverge, we must use the Alternating Series test. 

The test states that for a given series where  or  where  for all n, if  and  is a decreasing sequence, then  is convergent.

First, we must evaluate the limit of  as n approaches infinity:

The limit equals zero because the numerator of the fraction equals zero as n approaches infinity. 

Next, we must determine if  is a decreasing sequence. , thus the sequence is decreasing.

Because both parts of the test passed, the series is (absolutely) convergent.

Example Question #1 : Harmonic Series

Consider the alternating series

.

Which of the following tests for convergence is NOT conclusive?

Possible Answers:

The root test

The alternating series test

The limit test for divergence

The ratio test

Correct answer:

The limit test for divergence

Explanation:

Let

be the nth summand in the series. The limit test for divergence states that

implies that the series diverges.

However,

,

so the test is inconclusive.

Example Question #5 : Harmonic Series

Does the following series converge?

Possible Answers:

Cannot be determined

No

Yes

Correct answer:

No

Explanation:

No the series does not converge. The given problem is the harmonic series, which diverges to infinity.

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