-12x2 +8x +20 = 0
ax2 bx c = 0
a = -12
b = 8
c = 20
Δ = b2-4ac
Δ = 8² - (4 * -12 * 20)
Δ = 64 - (4*-240)
Δ = 64 - (-960)
Δ = 1024 Δ > 0
-12x2+8x+20=0
x = -b ∓ √Δ 2a
x' = -8 - √1024 2*-12 = -8 - 32.0 -24 = -40.0 -24 = 1.66666666667
x" = -8 + √1024 2*-12 = -8 + 32.0 -24 = 24.0 -24 = -1.0
x' = 240.0
x" = -144.0
S = {x ∈ R / x' = 240.0, x" = -144.0 }