Math 1 · Unit 9 · Lesson 3 · part 1 of 5
The Words We Use
The vocabulary for this lesson, in one place.
Words we use
| Word | Plain English | What you do |
|---|---|---|
| Geometric sequence | A list that multiplies by the same number each time. | Its dots sit on an exponential curve. |
| Common ratio, r | The number multiplied each time. It is the growth or decay factor, the b of Unit 7. | Divide any term by the one before. It can be a fraction. |
| Recursive rule | How to get the next term from the one before. The stairs. | a1 = start, an = r · an − 1. |
| Explicit rule | How to find any term from its term number. The elevator. | an = a1 · rn − 1. |
| Grows or shrinks | r bigger than 1 grows; r between 0 and 1 shrinks. | Compare r with 1. |
| Never zero | A shrinking geometric sequence gets close to 0 but never reaches it. | The x-axis is the asymptote. |