2)=0 x(x)=Cx+C2→c2=0c+C2=0→C1=C2 (3) a>0 X(x)=C Vix+C, sin ix X(0)=0→ X(=0→c:sn√=0 →非零解C2≠0sm A=0 nTa X(x)=C, sir C2是积分常数。 n兀 :本征值 X+X=0 :本征值方程 n X(xC:本征函数(2)  = 0 1 2 X(x) =C x +C  C2 = 0 0 C1 l +C2 =  C1 =C2 = 0 (3)   0 X (x) C cos  x C sin  x = 1 + 2 X (0) = 0  C1 = 0 X (l) = 0.  sin 0 C2 l =  非零解 sin l = 0 2 2 2 l n   = l n x X x C  ( ) = 2 sin 2 2 2 l n   = ：本征值 l n x X x C  ( ) = 2 sin ：本征函数 X ''+X = 0; ：本征值方程 C2是积分常数。 0 n =1,2,3 C2 