
Answers to the practice problems for Exam 2
Math 231 A1, Summer 2008
19. 8, by the geometric series formula.
21. 4/3, by the geometric series formula.
22. 12/5, by the geometric series formula.
25. diverges, by the kth-term test or the integral test.
26. diverges, by the kth-term test.
27. converges, by the alternating series test.
28. diverges, by the integral test or the limit comparison test with P1/k1/2.
29. diverges, since it is 3 times a p-series with p < 1.
30. converges, since it is 2 times a p-series with p > 1.
31. converges, by the converges by comparison (or limit comparison) with P1/k5/2.
32. diverges, by the limit comparison test with P1/k1/2.
33. converges, by the alternating series test or the ratio test.
34. diverges, by the kth-term test or the ratio test or the root test.
35. converges, by the alternating series test.
36. converges, by noticing that coskπ = (−1)kand then using the alternating series test.
37. converges, by the integral test, or the comparison test or limit comparison test with P2/k2.
38. diverges, by the integral test.
39. diverges, by the kth-term test or the ratio test.
40. converges, by the ratio test or root test.
41. converges, by the integral test, or the comparison test or limit comparison test with P1/k2.
42. diverges, by the integral test.
43. converges, by the ratio test.
44. diverges, by the limit comparison test with P1/k.
45. converges (by the alternating series test), but only conditionally (use the integral test or the limit
comparison test with P1/k when testing for absolute convergence).
46. converges (by the alternating series test), but only conditionally (use the integral test or the limit
comparison test with P1/k when testing for absolute convergence).
47. converges absolutely by comparison with P1/k3/2
48. converges (by the alternating series test), but only conditionally (use the comparison test with P3/k
when testing for absolute convergence).
49. converges for p > 1 (by the integral test or the limit comparison test for P1/kp).