-15x2 -3x +18 = 0
ax2 bx c = 0
a = -15
b = -3
c = 18
Δ = b2-4ac
Δ = -3² - (4 * -15 * 18)
Δ = 9 - (4*-270)
Δ = 9 - (-1080)
Δ = 1089 Δ > 0
-15x2-3x+18=0
x = -b ∓ √Δ 2a
x' = 3 - √1089 2*-15 = 3 - 33.0 -30 = -30.0 -30 = 1.0
x" = 3 + √1089 2*-15 = 3 + 33.0 -30 = 36.0 -30 = -1.2
x' = 225.0
x" = -270.0
S = {x ∈ R / x' = 225.0, x" = -270.0 }