1x2 +x -2 = 0
ax2 bx c = 0
a = 1
b = 1
c = -2
Δ = b2-4ac
Δ = ² - (4 * 1 * -2)
Δ = 1 - (4*-2)
Δ = 1 - (-8)
Δ = 9 Δ > 0
x2+x-2=0
x = -b ∓ √Δ 2a
x' = -1 - √9 2*1 = -1 - 3.0 2 = -4.0 2 = -2.0
x" = -1 + √9 2*1 = -1 + 3.0 2 = 2.0 2 = 1.0
x' = -2.0
x" = 1.0
S = {x ∈ R / x' = -2.0, x" = 1.0 }