-1x2 -6x +7 = 0
ax2 bx c = 0
a = -1
b = -6
c = 7
Δ = b2-4ac
Δ = -6² - (4 * -1 * 7)
Δ = 36 - (4*-7)
Δ = 36 - (-28)
Δ = 64 Δ > 0
-x2-6x+7=0
x = -b ∓ √Δ 2a
x' = 6 - √64 2*-1 = 6 - 8.0 -2 = -2.0 -2 = 1.0
x" = 6 + √64 2*-1 = 6 + 8.0 -2 = 14.0 -2 = -7.0
x' = 1.0
x" = -7.0
S = {x ∈ R / x' = 1.0, x" = -7.0 }