, : U(0,t)=0; U(l,t)=0; f(x,t)=A*sin(w*t)
U(x,0)=0; w=ka/l, k=1,2,3,4...; dU/dt=0 t=0.
C ?
. d^2U/dt^2=(a^2)*d^2U/dx^2+f(x,t). ?
( @ 25.9.2010, 10:57)

d^2U/dt^2=(a^2)*d^2U/dx^2+f(x,t). ?
.
, - . . w(x,t)=∑ n Tn(t)*sin(nx/l)
( @ 25.9.2010, 11:27)

, - .
.
.. .
w(x,t)=∑ n Tn(t)*sin(nx/l)
, . . , w(x,t). .