2.利用上题证明 In(1-x) 3.用逐项微分或逐项积分求下列级数的和: (2)nx (3)∑n(n+1) n(2n-1) (-1)”n f(n+1)! 4n-1 n十 4.求下列级数的和 (1) n(2n+1) 5.证明 ∑满足方程y2. 利用上题证明 1 2 0 1 1 (1 ) 1 n n x dx x n = − = − . 3. 用逐项微分或逐项积分求下列级数的和: ⑴ 1 n n x n = ; ⑵ 1 n n nx = ; ⑶ 1 ( 1) n n n n x = + ; ⑷ 1 2 1 ( 1) (2 1) n n n x n n − = − − ; ⑸ 2 1 1 !2 n n n n x n = + ; ⑹ 3 1 ( 1) ( 1)! n n n n x n = − + ; ⑺ 4 1 0 4 1 n n x n − = + ; ⑻ 1 0 (2 1) n n n x + = − ; ⑼ 2 1 1 n n n x − = ; ⑽ 2 2 1 1 (2 1) ! n n n x n + = + . 4. 求下列级数的和: ⑴ 1 2 1 2 n n n = − ; ⑵ 1 1 n n n (2 1) = + . 5. 证明: ⑴ 4 0 (4 )! n n x n = 满足方程 (4) y y = ;