8. Solve the wave equation
, 0<x<L, t>0 subject to the given conditions ,u(0,t)=0,u(L,t)=0 ,t>0,and u(x,0)=x(L-x),
,0<x<L .(10%)
8. Solve the wave equation
, 0<x<L, t>0 subject to the given conditions ,u(0,t)=0,u(L,t)=0 ,t>0,and u(x,0)=x(L-x),
,0<x<L .(10%)