-4x2 -9x -2 = 0
ax2 bx c = 0
a = -4
b = -9
c = -2
Δ = b2-4ac
Δ = -9² - (4 * -4 * -2)
Δ = 81 - (4*8)
Δ = 81 - (32)
Δ = 49 Δ > 0
-4x2-9x-2=0
x = -b ∓ √Δ 2a
x' = 9 - √49 2*-4 = 9 - 7.0 -8 = 2.0 -8 = -0.25
x" = 9 + √49 2*-4 = 9 + 7.0 -8 = 16.0 -8 = -2.0
x' = -4.0
x" = -32.0
S = {x ∈ R / x' = -4.0, x" = -32.0 }