分离变量+a2T=0 X"+λX=0(0):=0k(+hx()=0 A>0 X(x)=C, cos ax+ C2 sin vax X(x)=√AC2cos√Ax-Clsn√4x AX(0)=0國2= xX(O)+hN=0國→ X()+bX(D)=C[cos√l-hλsn√=0 cgl=h√'' 0; 2 T +a T = X ''+X = 0; X '(0) = 0 X (l) + hX '(l) = 0.   0 X (x) C cos  x C sin  x = 1 + 2 X '(0) = 0  C2 = 0 '( ) [ cos sin ] 2 1 X x =  C  x −C  x X (l) + hX '(l) = 0.  X (l) + hX '(l) = C1 [cos l − h  sin l] = 0 分离变量 ctg l = h 