四、例题 u+x 求解初值间题:14(x,0)=0 l(x,0)=0 解:由式8>可得: I ct rx+(t-t) A{x+(-7)3-[x-(t-7)d 0四、例题 求解初值问题： ï î ï í ì = = = + ( ,0) 0 ( ,0) 0 u x u x u u x t tt xx 解：由式<8>可得： ò ò + - - - = t x t x t u x t d 0 ( ) 2 ( ) 1 ( , ) t t a a t t a ò = + - - - - t x t x t d 0 2 2 {[ ( )] [ ( )] } 4 1 2 2 1 = xt