Chapter 7: Q 49. (page 615)

Determine whether the series $\sum_{j = 2}^{\infty} \frac{2^{j}}{3}$ converges or diverges. Give the sum of the convergent series.

Short Answer

Expert verified

The series $\sum_{j = 2}^{\infty} \frac{2^{j}}{3}$ diverges.

Step by step solution

Step 1. Given information.

Given a series $\sum_{j = 2}^{\infty} \frac{2^{j}}{3}$ .

Step 2. Find if the series converges or not.

The index starts with 2, rather than 0.

Note that the convergence of a series depends not upon the first few terms but only upon the tail of the series.

The standard form of a geometric series is $\sum_{k = 0}^{\infty} c r^{k}$ .

The geometric series converges if and only if $|r| < 1$ .

Here, the series $\sum_{j = 2}^{\infty} \frac{2^{j}}{3}$ has $c = \frac{1}{3}$ and $r = 2$ .

Since $r = 2$ , it follows that the series $\sum_{j = 2}^{\infty} \frac{2^{j}}{3}$ diverges.

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Determine whether the series $\sum_{j = 2}^{\infty} \frac{2^{j}}{3}$ converges or diverges. Give the sum of the convergent series.

Short Answer

Step by step solution

Step 1. Given information.

Step 2. Find if the series converges or not.

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Determine whether the series ∑j=2∞2j3converges or diverges. Give the sum of the convergent series.

Short Answer

Step by step solution

Step 1. Given information.

Step 2. Find if the series converges or not.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Logic and Functions

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Study anywhere. Anytime. Across all devices.

Determine whether the series $\sum_{j = 2}^{\infty} \frac{2^{j}}{3}$ converges or diverges. Give the sum of the convergent series.