Question

Which geometric series converges?

Answer 1

Answer:

Option 2: 1 + 1/2 + 1/4 + 1/8+...

Step-by-step explanation:

When a geometric series converges, it has a common ratio that is in between -1 and 1. We can start by finding the common ratios of all the options and then see which one converges.

In the first option, each term is 3 times the term before it, meaning it has a ratio of 3. 3 does not fit in the range we defined, so this series does not converge.

In the second option, each term is half the term before it. This means the common ratio is 1/2. 1/2 is in the range, so this series converges.

In the third option, we can see that the common ratio is -4 since it is the number being brought to a power. -4 does not fit in the range we defined, so this series does not converge.

In the fourth option, we can see the common ratio is 2 since it is the number you multiply by tone more time to get the next term. 2 does not fit in the range we defined, so this series does not converge.

From this, we can see the second option(1 + 1/2 + 1/4 + 1/8+...) is the solution.