-1x2 +11x +12 = 0
ax2 bx c = 0
a = -1
b = 11
c = 12
Δ = b2-4ac
Δ = 11² - (4 * -1 * 12)
Δ = 121 - (4*-12)
Δ = 121 - (-48)
Δ = 169 Δ > 0
-x2+11x+12=0
x = -b ∓ √Δ 2a
x' = -11 - √169 2*-1 = -11 - 13.0 -2 = -24.0 -2 = 12.0
x" = -11 + √169 2*-1 = -11 + 13.0 -2 = 2.0 -2 = -1.0
x' = 12.0
x" = -1.0
S = {x ∈ R / x' = 12.0, x" = -1.0 }