Part A

Directions: Use the formula Sn =a (1 - rn ) ÷ (1 – r) to find the sum Sn for each of the geometric series, given the value for a, r, and n.

1. a = -1, r = -2, n = 8

2. a = ½, r = -1/3, n = 6

3. a = 4, r = 3, n = 5

4. a = -9, r = -3, n =4

5. a = 6, r = 3, n =4

6. a = 4, r = ¼, n = 4

7. a = 3, r = -2, n = 7

8. a = -2, r = 3, n = 5

Part B

Directions: Use the formula Sn =a (1 - rn ) ÷ (1 – r) to find the sum Sn for each of the infinite and finite geometric series.

9. The first 9 terms of 12, – 6 ,+ 3, - …

10. The first 15 terms of -1, + 1, -…

11. The first 6 terms of 1, + 3, + …

12. The first 10 terms of 2, – 4, + …