-4x2 +13x -9 = 0
ax2 bx c = 0
a = -4
b = 13
c = -9
Δ = b2-4ac
Δ = 13² - (4 * -4 * -9)
Δ = 169 - (4*36)
Δ = 169 - (144)
Δ = 25 Δ > 0
-4x2+13x-9=0
x = -b ∓ √Δ 2a
x' = -13 - √25 2*-4 = -13 - 5.0 -8 = -18.0 -8 = 2.25
x" = -13 + √25 2*-4 = -13 + 5.0 -8 = -8.0 -8 = 1.0
x' = 36.0
x" = 16.0
S = {x ∈ R / x' = 36.0, x" = 16.0 }