Solve this quadratic equation using the quadratic formula.

x2 - 6x + 6 = 0

Hello : 
the discriminat of each quadratic equation : ax²+bx+c=0 (a ≠ 0) is :
Δ = b² -4ac
1 )  Δ > 0  the equation has two reals solutions : x =  (-b±√Δ)/2a
2 ) Δ = 0 : one solution : x = -b/2a
3 ) Δ < 0 : no reals solutions
in this exercice : x2 - 6x + 6 = 0a =1   b =-6      c=6
calculate : Δ