Sum of a Geometric Series

Finite Geometric Series. In this free math video tutorial by Mario's Math Tutoring we discuss how to find the sum of a finite geometric series and work through some example problems.

0:13 What is a finite geometric series
0:34 Formula for finding the sum of a finite geometric series
1:08 Example 1 Finding the sum given a series in summation notation
3:18 Example 2 Finding the sum of the first 20 terms

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[christianmatson]

+Mariosmathtutoring Thank you SO Its crazy that now I now understand this more from your video rather than from what my teacher taught me!!!

[danielstewart]

Short and sweet. Thanks for the refresher.

[claireg]

Your videos help me so much!! They really make me understand why formulas work :))) Thank you so much.

[bongo_baller]

thanks again for helping with my homework!

[kdragon]

What happens when n=0.
Do i add one to n?

[landonschannel]

I have a question. I am working through some problems and the very last one in the chapter on finite geometric series asks: Given the partial sums S3= -49/8, S4 = -105/16, and S5= -217/32 find the common ratio. I have tried systems of equations every which way I can think of and cannot solve the problem. Can you please help?

[persiankingish]

There's another formula where it's (r)^n -1 instead of 1-(r)^n. How do we decide when to use which formula?

[Noah-blld]

3:07
since it ends with a ...
don't we use the infinite equation?