_ 



-~ 



a:- 3 



(13) a + 6 = ^, 



a - A 6 - a 



(14) ( a; -9)(a;-7)(x-5)(a ; -l) 



(15) (a + *)* + (6 + *)* = (a - 6)*, 



^ ; 



(x + c) (x + d) (x -c)(x- 

 (x-c)(x-d) + (x + c)(x + d ) ' 



_5_ 5 1 8 1 



' + ~ + 



(18) 



1 2 9 14 7 



" 1 



(20) 



x lf + 1 4- ( -- l) lf = 2 (x -h a; + 1)' + Ux' (x 9 -f x 4 1 )', 

 (24) lG.r(* + l)(x + 2)(a: + 3) 



.c 4-4 = 0, 



