Geometric Series & Applications

These lessons, with videos, examples and step-by-step solutions, help High School students learn to derive the formula for the sum of a finite geometric series (when the common ratio is not 1), and use the formula to solve problems. For example, calculate mortgage payments.

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Related Pages
Geometric Sequence
Common Core (Algebra)
Common Core for Mathematics

Suggested Learning Targets

  • Develop the formula for the sum of a finite geometric series when the ratio is not 1.

  • Use the formula to solve real world problems such as calculate mortgage payments.

Common Core: HSA-SSE.B.4

The following diagrams show to derive the formula for the sum of a finite geometric series. Scroll down the page for more examples and solutions of geometric series.

Derive Geometric Series Formula

Derive Formula for finite geometric series

Geometric Series (How to Find the Sum of a Sequence)
How can you find the sum of a geometric series when you’re given only the first few terms and the last one? There are two formulas, and I show you how to do it. You need to find “n” for the last term.

Geometric series sum to figure out mortgage payments
Figuring out the formula for fixed mortgage payments using the sum of a geometric series.

Geometric Series Application - Total Income with Doubling Pay
This video provides an application problem that can be modeled by the sum of an a geometric sequence dealing with total income with pay doubling everyday.

A company offers to pay you $0.10 for the first day, $0.20 for the second day, $0.40 for the third day, $0.80 for the fourth day, and so on. What would your total income be after 1 month (30 days)?

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.
Mathway Calculator Widget

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