46 BOOK OF MATHEMATICAL PROBLEMS. 



1 1 3' (2-l)* 



W 1 + 2+2 +2"+ .. ..+ 2 



:= A 7> T ^ ~ T ~s 



O 2?i 



1 2 6 12 n(n + l) 



2 + 2+2+ 2 + + 2~~ 



S J L J_ ("!)" 



"1.2 2.3 3.4- + (n+l)(w + 



... tow quotients 

 1 1 



r+1 (r+l)(r + 2) (r + l)(r + 2)(r + 3) 

 + ... to 7i terms, 



a? 4a; n'x 



^+ 3-2a; + ...... + w + 1 - TWC 



x* x* - 



x* x* 



_ 

 1+ 1+ 2 +.. .. 



= 1 ^^ 



r + 1 



* + 7 w~^ r^ 



1 1 16 81 n< _ TT' 



1+3+ 5+7 + + 2?T+T + ... to oo~ 12' 



1149 n s 



