oo ∑"+x=zn"+∑ n H-=1 ∑nx"=x∑ n=1 n=1 令s(x)=∑mxn1积分 nE ∫(x)=∑x=12 -1 求导 →S1(x)=1 ∑ nx=rS,(r n=1 b)(-1<X<n n x n n = + 1 2 1   = = = + 1 1 1 n n n n x n nx   = = − = 1 1 1 n n n n nx x nx 令 = − = 1 1 1 ( ) n n s x nx 积分  = = x n n s x dx x 0 1 1 ( ) x x x − = − − − = 1 1 1 1 1 2 (1 ) 1 ( ) x s x −  = =  = 1 1( ) n n nx xs x 2 ( 1 x ) x− = (− 1  x  1 ) 求导