43 S Sopra le Serie. 



"V Soluzione. 



a — a-' y <z* 0,0" 4a~' a-* , 6 



2 j/ — I ^ 16 i6 i6 ~^ 



fu >4 / ab-a-'b-' . a'b'' j,a-b' ^cr' 



^2|/ I^ l6 IO I 



fen. f/» + ^)'* = ( — >• V = - 3 ^: + + — 



[6 1 6 1 6 



fen. 



ab'—a-'b-'. a'b^ 4a'b* ^ar^b-'^ 





6 i6 ■ ) i6 



, (T-'b-' 6 



^ 7k f~~l - *'■■ 



lo ló 



^2(/ — 1 ' i6 i6 10 



a-'^b-" 6 





,_2« 



/ —I ^ Tó ló 16 



a-'b-'" 6 



-4 .. 



' i6 ' l6 



Sarà dunque S = -- a' (^i -{-b* -\-b^ ~\-b'^ +^'") 



^-^a-'(i-^b-'^^b-^J^b-'' + b-'') 



—-a'(^i~{-b'-{-b* + b' + ^") '■" 



t , -^ -'1 , fi 



— ^- = (^i_[_£,-^_}_^-4_}_^-« 4-^"'") i 



+ — — — -' = - aU -— ) J rt- V -— — j 



I /,=" + '_ I I , è- =■- - = — I . 6 (« + i) . 

 a ( —, ) «~ ( ) A — ^^ 



I ^4._^,4-. + 4_^-4 4. j 



= rt* ( J 



I6 ^ 2_/,4_3-+ -/ 



