于是f(x)在(-0n+0)内的展开式为: (x)=m∑(os n7(2-x) L 令△L=2于是(5)为 (x)=lim 2AL /(5)cos x(E S)d5 t o daf f(s)cos a(5-x)dE0.8 1 0.6 0.4 0.2 0 x t 0 0.5 1 1.5 2 −1 −0.5 0 0.5 1 n 7 于是f(x)在(-∞,+∞)内的展开式为： 1 1 ( ) ( ) lim ( )cos (5) L L L n n x f x f d L L      →+ − = − =   令 L 于是(5)为： L   = 0 1 1 ( ) ( ) lim ( )cos L n n x f x L f d L       +  → − = − =    0 1 d f x d      ( )cos ( )  + + − = −  