-12x2 -20x +13 = 0
ax2 bx c = 0
a = -12
b = -20
c = 13
Δ = b2-4ac
Δ = -20² - (4 * -12 * 13)
Δ = 400 - (4*-156)
Δ = 400 - (-624)
Δ = 1024 Δ > 0
-12x2-20x+13=0
x = -b ∓ √Δ 2a
x' = 20 - √1024 2*-12 = 20 - 32.0 -24 = -12.0 -24 = 0.5
x" = 20 + √1024 2*-12 = 20 + 32.0 -24 = 52.0 -24 = -2.16666666667
x' = 72.0
x" = -312.0
S = {x ∈ R / x' = 72.0, x" = -312.0 }