-3x2 +15x +18 = 0
ax2 bx c = 0
a = -3
b = 15
c = 18
Δ = b2-4ac
Δ = 15² - (4 * -3 * 18)
Δ = 225 - (4*-54)
Δ = 225 - (-216)
Δ = 441 Δ > 0
-3x2+15x+18=0
x = -b ∓ √Δ 2a
x' = -15 - √441 2*-3 = -15 - 21.0 -6 = -36.0 -6 = 6.0
x" = -15 + √441 2*-3 = -15 + 21.0 -6 = 6.0 -6 = -1.0
x' = 54.0
x" = -9.0
S = {x ∈ R / x' = 54.0, x" = -9.0 }