-3x2 +18x -15 = 0
ax2 bx c = 0
a = -3
b = 18
c = -15
Δ = b2-4ac
Δ = 18² - (4 * -3 * -15)
Δ = 324 - (4*45)
Δ = 324 - (180)
Δ = 144 Δ > 0
-3x2+18x-15=0
x = -b ∓ √Δ 2a
x' = -18 - √144 2*-3 = -18 - 12.0 -6 = -30.0 -6 = 5.0
x" = -18 + √144 2*-3 = -18 + 12.0 -6 = -6.0 -6 = 1.0
x' = 45.0
x" = 9.0
S = {x ∈ R / x' = 45.0, x" = 9.0 }