Plz help me solve 3 a and 3b

(3) Find the domain of convergence of each series (note: whereas the first two cases are power series (centred at zero and at one, respectively), the other cases are not even power series at all!): (a) E n=1 (b ) (-1)"(x - 1)n M 2" (3n - 1) n=1 1 (c ) > n(1 + x2)n' n=1 - x n (d) E n' 1+x n=1 ent (e) E n2 - n+1 n=1 Answer: (a) I = [-1, 1]; (b) I = (-1,3]; (c) I = R \\ {0} = (-00, 0) U (0, too); (d) I = (0, too); and (e) I = (-oo, 0]