Respostas

2014-06-03T08:34:28-03:00
X²-8x-9=0
a=1 b=(-8) c=(-9)

b²-4ac
(-8)²-4.(1).(-9)
64+36
=100

-b+/-raiz de delta/2.a
-(-8)+/- raiz de 100/2.1
8+/-10/2

x'= 8+10/2 = 18/2 = 9

x'' = 8-10/2 = -2/2 = -1

S{-1,9)