1. 6.8A-Geometric Sequence Objective – TSW use geometric sequences.

2. Vocabulary for sequences:

3. Geometric Sequence: has a common ratio “r” which is multiplied to each previous term. 1. To find missing terms – same as an arithmetic sequence, but just a different formula since we are multiplying instead of adding to previous terms. 2. Remember to use your order of operations when solving (PEMDAS) 3. Plug what you know into the following formula: a n = a 1 r (n-1)

4. Examples: Write an equation for the nth term of a geometric sequence. Remember a n and “n” stay in the equation…they are your x and y! 1. 0.5, 2, 8, 32,…2. a 4 = 5, r = 6

5. You Try! 3. -0.25, 2, -16, 128,…4. a 3 = 16, r = 4

6. Find the indicated term for the geometric sequence. 5. a 1 = 800, r = 1/2, n = 66.

7. 7. Find two geometric means between –2 and 54 -2, ____, ____, 54 -2 54 4 NA x The two geometric means are 6 and -18, since –2, 6, -18, 54 forms an geometric sequence

8. Homework… Pgs. 700-702 #’s 19- 39(odds), 78-80(all)