Math Problem Statement

explain this

Explain why the series \( \sum_{n=1}^{\infty} \frac{n+1}{n} \) diverges.

Solution

This image appears to be an explanation about the divergence of a series. Let’s break it down.

The series in question is:

n=1n+1n\sum_{n=1}^{\infty} \frac{n+1}{n}

Step-by-Step Explanation:

  1. Expression of the General Term: The term inside the summation is n+1n\frac{n+1}{n}. This can be simplified as:

    n+1n=1+1n\frac{n+1}{n} = 1 + \frac{1}{n}

    So the general term is the sum of two components: 1 and 1n\frac{1}{n}.

  2. Analyzing the Limit: The series diverges because the term n+1n\frac{n+1}{n} does not approach zero as nn \to \infty. Instead, we calculate the limit of the general term as nn \to \infty:

    limnn+1n=limn(1+1n)=1+0=1\lim_{n \to \infty} \frac{n+1}{n} = \lim_{n \to \infty} \left( 1 + \frac{1}{n} \right) = 1 + 0 = 1

  3. Test for Divergence: For a series an\sum a_n to converge, a necessary condition is that:

    limnan=0\lim_{n \to \infty} a_n = 0

    In this case, since the limit of the general term is 1, the series fails this test, and therefore, the series diverges.

Conclusion:

The series diverges because the general term does not approach zero but instead tends to 1. Since the limit of the general term does not go to zero, we can conclude that the series cannot converge.

Would you like further clarification or a more in-depth explanation?

Here are 5 related questions you could explore:

  1. What is the test for convergence of a series?
  2. How does the comparison test work in determining the convergence of a series?
  3. What is the difference between an absolutely convergent and conditionally convergent series?
  4. How do you apply the ratio test to a series?
  5. What happens when the limit of a series' terms is greater than 0?

Tip: Always check the limit of the general term of a series when determining convergence or divergence. If it doesn’t approach zero, the series cannot converge.

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Math Problem Analysis

Mathematical Concepts

Infinite Series
Divergence Test
Limits

Formulas

\( a_n = \frac{n+1}{n} = 1 + \frac{1}{n} \)
\( \lim_{n \to \infty} a_n \)

Theorems

Test for Divergence

Suitable Grade Level

Grades 11-12