-3x2 -9x +12 = 0
ax2 bx c = 0
a = -3
b = -9
c = 12
Δ = b2-4ac
Δ = -9² - (4 * -3 * 12)
Δ = 81 - (4*-36)
Δ = 81 - (-144)
Δ = 225 Δ > 0
-3x2-9x+12=0
x = -b ∓ √Δ 2a
x' = 9 - √225 2*-3 = 9 - 15.0 -6 = -6.0 -6 = 1.0
x" = 9 + √225 2*-3 = 9 + 15.0 -6 = 24.0 -6 = -4.0
x' = 9.0
x" = -36.0
S = {x ∈ R / x' = 9.0, x" = -36.0 }