§2.幂级数 1.求下列各幂级数的收敛域 (2) In(n+D) n+1 =l(n n (6) (2n+1)! () (-1)x2 +-+ 第5页共9页第 5 页 共 9 页 §2. 幂级数 1． 求下列各幂级数的收敛域. ⑴ 1 (2 ) ; ! n n x n  =  ⑵ 1 1 ln( 1) ; 1 n n n x n  + = + +  ⑶ 1 1 ; n n n n x n  =     +            ⑷ 2 1 ; 2 n n n x  =  ⑸ 1 3 ( 1) ; n n n n x n  =   + −    ⑹ 1 3 ( 2) ( 1) ; n n n n x n  = + −  + ⑺ 1 (2 )!! ; (2 1)!! n n n x n  = +  ⑻ 2 1 1 1 ; n n n x n −  =     +    ⑼ 1 ( 1) ; n n n n x n n  = −  ⑽ 1 ; 5 7 n n n n x  = +  ⑾ 2 1 ( !) ; (2 )! n n n x n  =  ⑿ 1 1 1 1 ; 2 n n x n  =     + +  +    ⒀ 1 ; n n nx  = 