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| − | A geshgeshsdhSDhrjfd | + | A '''geometric progression''' is a [[sequence]] of numbers that has a constant [[ratio]] of each term to its preceding term. For example, this is a geometric progression: 2, 4, 8, 16, 32. |
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| | + | In finance, [[compound interest]] is an example of a geometric progression. An example would be a bank account that earns an API (annual percentage interest) rate of 5% per year. Every year, the number of dollars in the account is multiplied by the factor 1.05. That is about the same as doubling every fifteen years. |
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| | + | The sequence 2, 4, 8, 16, 32 is simply the "powers of two:" two, two squared, two cubed, two to the fourth power, and so on. This can be written using [[exponent]]s this way: |
| | + | ::2<sup>1</sup>, 2<sup>2</sup>, 2<sup>3</sup>, 2<sup>4</sup>, 2<sup>5</sup> |
| | + | This is why geometric progressions are sometimes called [[exponential growth]]. |
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| | ==Geometric series== | | ==Geometric series== |
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