-10x2 -9x -2 = 0
ax2 bx c = 0
a = -10
b = -9
c = -2
Δ = b2-4ac
Δ = -9² - (4 * -10 * -2)
Δ = 81 - (4*20)
Δ = 81 - (80)
Δ = 1 Δ > 0
-10x2-9x-2=0
x = -b ∓ √Δ 2a
x' = 9 - √1 2*-10 = 9 - 1.0 -20 = 8.0 -20 = -0.4
x" = 9 + √1 2*-10 = 9 + 1.0 -20 = 10.0 -20 = -0.5
x' = -40.0
x" = -50.0
S = {x ∈ R / x' = -40.0, x" = -50.0 }