-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 }