558                                                    18

.          -
       .     
 ,      
 . ,    ,   .

^^^^f      

      ,
   .      , -
        ,    
  .  ,  ,    
    ,     -
 ,           
.

        ?9    
,       ,  -
    ,     (  ,  
   ),      .  , 
        -
         :

D.+P,    D^     ^

'"--^-            "">

 D^  /^           / = 1.

   (18.30),      
 t = 1.     ,      -
  ,        .  
      t = 1 :

      ^    ,    ^3    ,__4    ,   _    

f    == _____________ + _____________ + ____________ -)-___==  J   _______________ ^                      / 1   1 \

(1+:)'   (l+k)2   (\+k)3      i=2(l+k)'~1

  (18.31)  .     (18.30)  -
 :

!    f   D!       D!       At      }l   1  \

y=   '  +    2   +    3  +    4  +... ____ =
{+k   [(l+k)1   (l+k)1   (\+k)3     l+k j

=  -   +   ^   .   ^   ^  4   , ^  A

(l+Vk)'   (l+k)2   (l+k)3   (l+k)4      >=i(l+^'

     (18.7).  ,   
         
         -
.  ,    ,     -
   .  ,  (18.7),    -
,    ,    , 