7. [15 marks] Determine whether the series is absolutely convergent, conditionally convergent, or divergent. a. (5 marks) [(-1)7 - 1 27 n=1 b. (5 marks) S(-1)"+1 cost n 1 + n2 n=1 c. (5 marks) (-1) 1 n=1 n + vn 8. [18 marks] Find the radius of convergence and the interval of convergence for the series. a. (6 marks) x 12 5n72 n= 1 b. (6 marks) (-1)nx2n iM (2n)! n=1 c. (6 marks) 2" (x - 2)" 47 + 1 n=1