-4x2 +9x -5 = 0
ax2 bx c = 0
a = -4
b = 9
c = -5
Δ = b2-4ac
Δ = 9² - (4 * -4 * -5)
Δ = 81 - (4*20)
Δ = 81 - (80)
Δ = 1 Δ > 0
-4x2+9x-5=0
x = -b ∓ √Δ 2a
x' = -9 - √1 2*-4 = -9 - 1.0 -8 = -10.0 -8 = 1.25
x" = -9 + √1 2*-4 = -9 + 1.0 -8 = -8.0 -8 = 1.0
x' = 20.0
x" = 16.0
S = {x ∈ R / x' = 20.0, x" = 16.0 }