-6x2 -11x +7 = 0
ax2 bx c = 0
a = -6
b = -11
c = 7
Δ = b2-4ac
Δ = -11² - (4 * -6 * 7)
Δ = 121 - (4*-42)
Δ = 121 - (-168)
Δ = 289 Δ > 0
-6x2-11x+7=0
x = -b ∓ √Δ 2a
x' = 11 - √289 2*-6 = 11 - 17.0 -12 = -6.0 -12 = 0.5
x" = 11 + √289 2*-6 = 11 + 17.0 -12 = 28.0 -12 = -2.33333333333
x' = 18.0
x" = -84.0
S = {x ∈ R / x' = 18.0, x" = -84.0 }