-4x2 +9x +13 = 0
ax2 bx c = 0
a = -4
b = 9
c = 13
Δ = b2-4ac
Δ = 9² - (4 * -4 * 13)
Δ = 81 - (4*-52)
Δ = 81 - (-208)
Δ = 289 Δ > 0
-4x2+9x+13=0
x = -b ∓ √Δ 2a
x' = -9 - √289 2*-4 = -9 - 17.0 -8 = -26.0 -8 = 3.25
x" = -9 + √289 2*-4 = -9 + 17.0 -8 = 8.0 -8 = -1.0
x' = 52.0
x" = -16.0
S = {x ∈ R / x' = 52.0, x" = -16.0 }