5x2 -13x -6 = 0
ax2 bx c = 0
a = 5
b = -13
c = -6
Δ = b2-4ac
Δ = -13² - (4 * 5 * -6)
Δ = 169 - (4*-30)
Δ = 169 - (-120)
Δ = 289 Δ > 0
5x2-13x-6=0
x = -b ∓ √Δ 2a
x' = 13 - √289 2*5 = 13 - 17.0 10 = -4.0 10 = -0.4
x" = 13 + √289 2*5 = 13 + 17.0 10 = 30.0 10 = 3.0
x' = -10.0
x" = 75.0
S = {x ∈ R / x' = -10.0, x" = 75.0 }