Class Date Name LESSON Practice A 12-4 Geometric Sequences and Series Determine whether the sequence could be geometric or arithmetic. If it is, find the common ratio or difference. 1. 768, 384, 192, 96, 48, ... a. Find the differences. b. Find the ratios. c. Name the type of sequence. Then identify the common difference or ratio. 2. 8, 20, 50, 125, 312.5, ... 3. 21, 13, 5, -3, -11, ... 4. 5, -10, 20, -40, 80, -160, ... 5. 1 , 2 , 4 , 7 , 11 , 16 , ... 6. 5, 10, 20, 40, 80, 160, ... 7. -1, 2, -4, 7, -11, 16, ... Find the 10th term of each geometric sequence. 8. 625, 125, 25, 5, 1, ... a. Find the common ratio. b. Evaluate an = a,r"- for n = 10. 9. 9600, -4800, 2400, -1200, ... 10. 1, 3, 9, 27, ... 11. 5500, 550, 55, 5.5, 0.55, ... 12. 4 4 4 4 81' 27'9'3' .. Find the geometric mean of each pair of numbers. 13. 10 and 40 14. 27 and 3 15. -5 and -45 Solve. 16. In his first year on the job, Matthew earned a salary of $20,000. He received a 5% raise each year. a. How much did he earn in his tenth year? b. What were his total earnings over the 10-year period? Copyright @ by Holt, Rinehart and Winston. 27 Holt Algebra 2 All rights reserved