Δ= (-8)^2 -4.1.7
Δ= 64- 28
Δ= 36
x1= -(-8) + 6/ 2.1
x1= 8 + 6/ 2
x1= 7
x2= -(-8) – 6/2.1
x2= 8-6/2
x2= 1
s= { 7 e 1}