-6x2 -19x +20 = 0
ax2 bx c = 0
a = -6
b = -19
c = 20
Δ = b2-4ac
Δ = -19² - (4 * -6 * 20)
Δ = 361 - (4*-120)
Δ = 361 - (-480)
Δ = 841 Δ > 0
-6x2-19x+20=0
x = -b ∓ √Δ 2a
x' = 19 - √841 2*-6 = 19 - 29.0 -12 = -10.0 -12 = 0.833333333333
x" = 19 + √841 2*-6 = 19 + 29.0 -12 = 48.0 -12 = -4.0
x' = 30.0
x" = -144.0
S = {x ∈ R / x' = 30.0, x" = -144.0 }