15x2 +12x -3 = 0
ax2 bx c = 0
a = 15
b = 12
c = -3
Δ = b2-4ac
Δ = 12² - (4 * 15 * -3)
Δ = 144 - (4*-45)
Δ = 144 - (-180)
Δ = 324 Δ > 0
15x2+12x-3=0
x = -b ∓ √Δ 2a
x' = -12 - √324 2*15 = -12 - 18.0 30 = -30.0 30 = -1.0
x" = -12 + √324 2*15 = -12 + 18.0 30 = 6.0 30 = 0.2
x' = -225.0
x" = 45.0
S = {x ∈ R / x' = -225.0, x" = 45.0 }