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 = -36.0 30 = -1.2
x" = -3 + √1089 2*15 = -3 + 33.0 30 = 30.0 30 = 1.0
x' = -270.0
x" = 225.0
S = {x ∈ R / x' = -270.0, x" = 225.0 }