Calculus 2 : Introduction to Series in Calculus

Study concepts, example questions & explanations for Calculus 2

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Example Questions

Example Question #4 : Concepts Of Convergence And Divergence

Which of following intervals of convergence cannot exist?

Possible Answers:

For any  such that , the interval 

For any , the interval  for some 

Correct answer:

Explanation:

 cannot be an interval of convergence because a theorem states that a radius has to be either nonzero and finite, or infinite (which would imply that it has interval of convergence ). Thus,  can never be an interval of convergence.

Example Question #5 : Concepts Of Convergence And Divergence

Which of the following statements is true regarding the following infinite series?

Possible Answers:

The series converges because 

The series diverges, by the divergence test, because the limit of the sequence  does not approach a value as 

The series diverges because  for some  and finite.

The series diverges to .

Correct answer:

The series diverges, by the divergence test, because the limit of the sequence  does not approach a value as 

Explanation:

The divergence tests states for a series , if  is either nonzero or does not exist, then the series diverges.

The limit  does not exist, so therefore the series diverges. 

Example Question #1 : Concepts Of Convergence And Divergence

Determine whether the following series converges or diverges:

Possible Answers:

The series conditionally converges.

The series diverges.

The series converges.

None of the other answers.

Correct answer:

The series converges.

Explanation:

To prove the series converges, the following must be true:

If converges, then converges.

Now, we simply evaluate the limit:

The shortcut that was used to evaluate the limit as n approaches infinity was that the coefficients of the highest powered term in numerator and denominator were divided.

The limit approaches a number (converges), so the series converges.  

Example Question #1 : Geometric Series

Determine whether the following series converges or diverges. If it converges, what does it converge to? 

Possible Answers:

Correct answer:

Explanation:

First, we reduce the series into a simpler form.

We know this series converges because

By the Geometric Series Theorem, the sum of this series is given by

Example Question #21 : Introduction To Series In Calculus

Determine whether the following series converges or diverges. If it converges, what does it converge to?

Possible Answers:

 

Correct answer:

Explanation:

Notice how this series can be rewritten as

Therefore this series diverges. 

Example Question #1 : Sequences & Series

There are 2 series,  and , and they are both convergent. Is  convergent, divergent, or inconclusive?

Possible Answers:

Convergent

Divergent

Inconclusive

Correct answer:

Convergent

Explanation:

Infinite series can be added and subtracted with each other.

Since the 2 series are convergent, the sum of the convergent infinite series is also convergent.

 

Note: The starting value, in this case n=1, must be the same before adding infinite series together.

Example Question #1 : Concepts Of Convergence And Divergence

You have a divergent series  , and you multiply it by a constant 10. Is the new series  convergent or divergent?

Possible Answers:

Convergent

Inconclusive

Divergent

Correct answer:

Divergent

Explanation:

This is a fundamental property of series.

For any constant c, if  is convergent then  is convergent, and if  is divergent,  is divergent.

 

 is divergent in the question, and the constant c is 10 in this case, so  is also divergent.

Example Question #21 : Series In Calculus

There are 2 series,  and , and they are both divergent. Is  convergent, divergent, or inconclusive?

Possible Answers:

Convergent

Inconclusive

Divergent

Correct answer:

Inconclusive

Explanation:

 is divergent

 is divergent

However, unlike convergent series in which the sum of convergent series will produce a convergent series, this is not the case for divergent series. Due to the nature of infinite series, adding together 2 divergent series may be divergent, but it may also produce a convergent series. More information is needed.

 is inconclusive

Example Question #22 : Series In Calculus

Use the limit test (divergence test) to find if the series is convergent, divergent, or inconclusive.

Possible Answers:

Inconclusive

Convergent

Divergent

Correct answer:

Inconclusive

Explanation:

Divergence Test and Limit Test are the same tests with different names.

If then  diverges.

However, if  the test is inconclusive.

Solution:

The series is inconclusive by the divergence test.

Example Question #23 : Series In Calculus

Use the limit test (divergence test) to find if the series is convergent, divergent, or inconclusive.

Possible Answers:

Convergent

Divergent

Inconclusive

Correct answer:

Inconclusive

Explanation:

Divergence Test and Limit Test are the same tests with different names.

If  then  diverges.

However, if  the test is inconclusive.

Solution:

This series is inconclusive by the divergence test.

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