5x2 +3x -8 = 0
ax2 bx c = 0
a = 5
b = 3
c = -8
Δ = b2-4ac
Δ = 3² - (4 * 5 * -8)
Δ = 9 - (4*-40)
Δ = 9 - (-160)
Δ = 169 Δ > 0
5x2+3x-8=0
x = -b ∓ √Δ 2a
x' = -3 - √169 2*5 = -3 - 13.0 10 = -16.0 10 = -1.6
x" = -3 + √169 2*5 = -3 + 13.0 10 = 10.0 10 = 1.0
x' = -40.0
x" = 25.0
S = {x ∈ R / x' = -40.0, x" = 25.0 }