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### Course: Calculus, all content (2017 edition)>Unit 7

Lesson 1: Sequences review

# Geometric sequence review

In a geometric sequence, the ratio between consecutive terms is always the same. Learn more about Geometric sequences and see some examples. Created by Sal Khan.

## Want to join the conversation?

• how do you make this easier to understand
• My general strategy for making any of the topics easier to understand is to watch the video a half dozen times and use pause to make sure I fully understand each step.

Is there something specific that is tripping you up?
• What is the best way to understand sigma in solving sequences?
• Sigma means sum. So when you have the sigma in front of a sequence definition, it means put a plus sign between each element and add them all up.
• what is the difference between 'series' and 'sequence' ?
• what is the difference between Arthimatic series and arthemitic sequence?
• A sequence is a list of terms.
A series is the sum of a sequence, that is, the sum of the list of terms.
So, sequence: Sn = { 1, 3, 5, 7, 9 }
Series: ΣSn = 1 + 3 + 5 + 7 + 9
• So how would I write an equation for the example at ?
(1 vote)
• Since the sequence is not being summed, then it can't be equated to anything so you can't write an equation (in the strictest sense of the term) for the example.

If you are merely trying to notate the sequence then:

`5•(1/7)^n for n = 0 to ∞`
• What is the difference between a geometric sequence and an exponential function?

(1 vote)
• They are quite similar, since in both a geometric sequence and an exponential function, the growth or decay factor is constant. The main difference is that the domain of an exponential function is all real numbers, while the domain of a geometric sequence (when the sequence is thought of as a function) is the positive integers.

Have a blessed, wonderful day!
• How do you identify whether it is a geometric or arithmetic sequence?
(1 vote)
• Geometric sequences change by a common ratio, arithmetic sequences change by a common difference. The common ration is determined by the division of the consecutive values in the sequence or series; the common difference, as you may guess by the name, is determined by subtracting the consecutive values in the sequence.