# The Geometric Series Formula (VIDEO!)

What is the geometric series formula? When is it valid? How do we derive the formula?

In this video we use a paper-tearing trick to show that the infinite formula is valid at least for some types of numbers (and this trick makes it so obvious that the formula is true in these cases. It’s neat!) We then discuss how to prove the formula true in general and for what range of values it holds. All easy and all fun!

Geometric Series Formula

• ## ON-LINE SHORT COURSES!

QUADRATICS, Permutations and Combinations, EXPLODING DOTS, and more!

Written for educators - and their students too! - this website, slowly growing, takes all the content Tanton has developed in his books, videos, and workshops, and organizes it into short, self-contained, and complete, curriculum units proving that mathematics, at all points of the school curriculum, can be joyous, fresh, innovative, rich, deep-thinking, and devoid of any rote doing! Let's teach generations of students to be self-reliant thinkers, willing to flail and to use their common sense to "nut their way" through challenges, to assess and judge results, and to adjust actions to find success. (Great life skills!)

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