x
2
- 6x + 8 = 0
applico la
formula risolutiva
6
[ 36 - 4(1)(8)]
x
1,2
= ----------------------------- =
2
6
4
= --------------- =
2
6
2
= -------------
2
quindi
x
1
= 2 x
2
= 4
[ 36 - 4(1)(8)]