1()=(-2x+)P(x) :P(x)=21(x2xP(x)+Pm(x)(3) dx ():(+1)m(x)(1+1)(x)-(21+)xP( 17(x)=0 (4) 由(4)xP(x)=P() 2l+112/+1 代入(3)即证(2)( ) ( ) ( ) 2 0 0 1- 2 l l l l l t P x t xt t P x t l ¥ ¥ = = å å = + ¢ ( ) ( ) ( ) ( ) ( ) 1 1 -1 : - 2 3 l l l l l t P x P x xP x P x + + = + ¢ ¢ ¢ (l +1) Pl ¢ ¢ +1 ( x) - (2l + + 1) Pl l ( x) - (2 1 l ) xP x( ) ( ) ( ) -1 0 4 l + = lP x ¢ 由(4) ( ) ( ) 1 -1 1 - - - 2 1 2 1 l l l l l l xP x P x P P l l + + ¢ = ¢ ¢ + + 代入(3)即证(2) ( ) 1 : d dx