Respostas

2013-11-14T20:04:00-02:00
X2 + x - 6 = 0
(x+3) ( x-2) = 0
x = -3 e x = 2

2) x2 - 9x + 20 
    x2 - 9x  + 20 = 0
   (x-5) ( x-4 ) = 0
  x = 5 , x = 4

-x2 +x + 2 = x2 -x -2
(x-2) (x+1) = 0
x = 2 x = -1

-x2 + 6x - 9 = x2 - 6x + 9 
( x-3 ) ( x-3 ) 
x1=x2=3