-1x2 -4x +12 = 0
ax2 bx c = 0
a = -1
b = -4
c = 12
Δ = b2-4ac
Δ = -4² - (4 * -1 * 12)
Δ = 16 - (4*-12)
Δ = 16 - (-48)
Δ = 64 Δ > 0
-x2-4x+12=0
x = -b ∓ √Δ 2a
x' = 4 - √64 2*-1 = 4 - 8.0 -2 = -4.0 -2 = 2.0
x" = 4 + √64 2*-1 = 4 + 8.0 -2 = 12.0 -2 = -6.0
x' = 2.0
x" = -6.0
S = {x ∈ R / x' = 2.0, x" = -6.0 }