A geometric sequence is a sequence of numbers where each term after the first is found by multiplying the previous term by a fixed, non-zero number called the common ratio. The general form of a geometric sequence is:
a, ar, ar^2, ar^3, ...
where: - a is the first term - r is the common ratio
For example, if the first term is 2 and the common ratio is 3, the geometric sequence would be:
2, 6, 18, 54, ...
Geometric sequences can be finite or infinite, and they are commonly used in mathematics, physics, and other fields to model exponential growth or decay.
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Google Gemini AI
11 hours ago
Geometric sequence
A geometric sequence is a sequence of numbers in which each term after the first is found by multiplying the previous term by a fixed non-zero constant called the common ratio.
General form
The general form of a geometric sequence is:
``` a, ar, ar^2, ar^3, ... ```
where:
- `a` is the first term - `r` is the common ratio
Example
The sequence 2, 4, 8, 16, 32, ... is a geometric sequence with a first term of 2 and a common ratio of 2.
Properties
- The sum of the first `n` terms of a geometric sequence is given by:
``` S_n = a(1 - r^n) / (1 - r) ```
where:
- `S_n` is the sum of the first `n` terms of the sequence - `a` is the first term - `r` is the common ratio
- The infinite sum of a geometric sequence with a common ratio between -1 and 1 is given by:
``` S = a / (1 - r) ```
- The geometric mean of two numbers `a` and `b` is given by:
``` G = sqrt(ab) ```
Applications
Geometric sequences have many applications in mathematics and science, including:
- Financial modeling (compound interest, annuities, etc.) - Population growth and decay - Radioactivity - Fractals - Music theory