Geometric Sequences

1. Homework Questions

2. Geometric Sequences

3. Geometric Sequences
 In a geometric sequence, the ratio between
consecutive terms is constant.
 This ratio is called the common ratio.
 To find r:
stterm
ndterm
1
2

4. Geometric, Arithmetic, Neither?
(find the next 2 terms if so)
1. 5, 15, 45, 135…
2. 15, 30, 45, 60…
3. 6, -24, 96, -384…
4. 8, 20, 32, 44…

5. Geometric Sequences Formulas
 Recursive Formula
 an = an-1 r
 Explicit Formula
 an = a1 rn-1
•
•

6. Find the 19th
term…
1. 11, 33, 99, 297…
2. 20, 17, 14, 11, 8…

7. FYI - Graphs
 Arithmetic Graphs are linear
 Geometric Graphs are exponential

8. Geometric Mean
 Geometric Mean =
3. 20, _____, 80
4. 3, ____, 18, 75
5. 28, ____, 5103
numbersproductof 2

9. Homework
 Worksheet!

10. Homework
 Worksheet!