5x2 -9x -2 = 0
ax2 bx c = 0
a = 5
b = -9
c = -2
Δ = b2-4ac
Δ = -9² - (4 * 5 * -2)
Δ = 81 - (4*-10)
Δ = 81 - (-40)
Δ = 121 Δ > 0
5x2-9x-2=0
x = -b ∓ √Δ 2a
x' = 9 - √121 2*5 = 9 - 11.0 10 = -2.0 10 = -0.2
x" = 9 + √121 2*5 = 9 + 11.0 10 = 20.0 10 = 2.0
x' = -5.0
x" = 50.0
S = {x ∈ R / x' = -5.0, x" = 50.0 }