13-5

This weekend I am going to teach you all how to work problems that require you to find infinite sums of geometric series. Before I show you all an example, there are a few things that you need to know about infinite sums.

Notes:
• You can only find the infinite sum of a geometric series, it will not work for an arithmetic series
• You can only find the infinite sum of a geometric series if r < 1
• The formula for finding the infinite sum of a geometric series is as follows:
S= ((t1) / (1-r))
• To find where an infinite geometric converges, set r < 1 and solve for x
• Another thing that you need to know about this section is how to write a repeating decimal as a fraction. To do this follow this formula: (what’s repeating / place-1)

Example: Find the sum of the infinite geometric series: 24-12+6-3
• S=t1 / 1-r = 24 / 1- (-1/2)
• S=24 / (3/2)
• S=16


-Braxton-