-3x2 +20x +7 = 0
ax2 bx c = 0
a = -3
b = 20
c = 7
Δ = b2-4ac
Δ = 20² - (4 * -3 * 7)
Δ = 400 - (4*-21)
Δ = 400 - (-84)
Δ = 484 Δ > 0
-3x2+20x+7=0
x = -b ∓ √Δ 2a
x' = -20 - √484 2*-3 = -20 - 22.0 -6 = -42.0 -6 = 7.0
x" = -20 + √484 2*-3 = -20 + 22.0 -6 = 2.0 -6 = -0.333333333333
x' = 63.0
x" = -3.0
S = {x ∈ R / x' = 63.0, x" = -3.0 }