U(t)=420te t 420te45t 420t lim u(t)=lim =420im 0 t→0 t→0 2.45t t->∞2.45e 2.45t du(t) 0,420e0(-√6t+1)=0 dt rm=、6=04090m=4208=03 63.1t t e t e V 6 t 2.45t ( ) 420 420 − −  = = t . s . e . V . . m 0 408 m 420 0 408 63 1 6 1 2 4 5 0 408 = = → =  = −     m = 63.1V t 0 t m 0 2.45 1 420lim 420 lim ( ) lim 2.45 2.45 = = = → → → t t t t t e e t  t 0, 420 ( 6 1) 0 ( ) 6 = − + = − e t dt d t  t