5x2 -x -6 = 0
ax2 bx c = 0
a = 5
b = -1
c = -6
Δ = b2-4ac
Δ = -² - (4 * 5 * -6)
Δ = 1 - (4*-30)
Δ = 1 - (-120)
Δ = 121 Δ > 0
5x2-x-6=0
x = -b ∓ √Δ 2a
x' = 1 - √121 2*5 = 1 - 11.0 10 = -10.0 10 = -1.0
x" = 1 + √121 2*5 = 1 + 11.0 10 = 12.0 10 = 1.2
x' = -25.0
x" = 30.0
S = {x ∈ R / x' = -25.0, x" = 30.0 }